[AggressiveInstCombine] Inline strcmp/strncmp #89371
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Inline calls to strcmp(s1, s2) and strncmp(s1, s2, N), where N and exactly one of s1 and s2 are constant.
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@llvm/pr-subscribers-llvm-analysis @llvm/pr-subscribers-llvm-transforms Author: Franklin Zhang (FLZ101) ChangesInline calls to strcmp(s1, s2) and strncmp(s1, s2, N), where N and exactly one of s1 and s2 are constant. For example: int res = strcmp(s, "ab");is converted to int res = (int)s[0] - (int)'a';
if (res != 0)
goto END;
res = (int)s[1] - (int)'b';
if (res != 0)
goto END;
res = (int)s[2] - (int)'\0';
END:Ported from a similar gcc feature Inline strcmp with small constant strings. Patch is 31.09 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/89371.diff 4 Files Affected:
diff --git a/llvm/lib/Transforms/AggressiveInstCombine/AggressiveInstCombine.cpp b/llvm/lib/Transforms/AggressiveInstCombine/AggressiveInstCombine.cpp
index e586e9eda1322f..eddd7382c27bbc 100644
--- a/llvm/lib/Transforms/AggressiveInstCombine/AggressiveInstCombine.cpp
+++ b/llvm/lib/Transforms/AggressiveInstCombine/AggressiveInstCombine.cpp
@@ -19,6 +19,7 @@
#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/BasicAliasAnalysis.h"
#include "llvm/Analysis/ConstantFolding.h"
+#include "llvm/Analysis/DomTreeUpdater.h"
#include "llvm/Analysis/GlobalsModRef.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/Analysis/TargetTransformInfo.h"
@@ -28,6 +29,7 @@
#include "llvm/IR/Function.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/PatternMatch.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/BuildLibCalls.h"
#include "llvm/Transforms/Utils/Local.h"
@@ -922,6 +924,251 @@ static bool foldPatternedLoads(Instruction &I, const DataLayout &DL) {
return true;
}
+static cl::opt<unsigned> StrNCmpInlineThreshold(
+ "strncmp-inline-threshold", cl::init(3), cl::Hidden,
+ cl::desc("The maximum length of a constant string for a builtin string cmp "
+ "call eligible for inlining. The default value is 3."));
+
+namespace {
+class StrNCmpInliner {
+public:
+ StrNCmpInliner(CallInst *CI, LibFunc Func, Function::iterator &BBNext,
+ DomTreeUpdater *DTU, const DataLayout &DL)
+ : CI(CI), Func(Func), BBNext(BBNext), DTU(DTU), DL(DL) {}
+
+ bool optimizeStrNCmp();
+
+private:
+ bool inlineCompare(Value *LHS, StringRef RHS, uint64_t N, bool Switched);
+
+ CallInst *CI;
+ LibFunc Func;
+ Function::iterator &BBNext;
+ DomTreeUpdater *DTU;
+ const DataLayout &DL;
+};
+
+} // namespace
+
+/// First we normalize calls to strncmp/strcmp to the form of
+/// compare(s1, s2, N), which means comparing first N bytes of s1 and s2
+/// (without considering '\0')
+///
+/// Examples:
+///
+/// \code
+/// strncmp(s, "a", 3) -> compare(s, "a", 2)
+/// strncmp(s, "abc", 3) -> compare(s, "abc", 3)
+/// strncmp(s, "a\0b", 3) -> compare(s, "a\0b", 2)
+/// strcmp(s, "a") -> compare(s, "a", 2)
+///
+/// char s2[] = {'a'}
+/// strncmp(s, s2, 3) -> compare(s, s2, 3)
+///
+/// char s2[] = {'a', 'b', 'c', 'd'}
+/// strncmp(s, s2, 3) -> compare(s, s2, 3)
+/// \endcode
+///
+/// We only handle cases that N and exactly one of s1 and s2 are constant. Cases
+/// that s1 and s2 are both constant are already handled by the instcombine
+/// pass.
+///
+/// We do not handle cases that N > StrNCmpInlineThreshold.
+///
+/// We also do not handles cases that N < 2, which are already
+/// handled by the instcombine pass.
+///
+bool StrNCmpInliner::optimizeStrNCmp() {
+ if (StrNCmpInlineThreshold < 2)
+ return false;
+
+ Value *Str1P = CI->getArgOperand(0);
+ Value *Str2P = CI->getArgOperand(1);
+ // should be handled elsewhere
+ if (Str1P == Str2P)
+ return false;
+
+ StringRef Str1, Str2;
+ bool HasStr1 = getConstantStringInfo(Str1P, Str1, false);
+ bool HasStr2 = getConstantStringInfo(Str2P, Str2, false);
+ if (!(HasStr1 ^ HasStr2))
+ return false;
+
+ // note that '\0' and characters after it are not trimmed
+ StringRef Str = HasStr1 ? Str1 : Str2;
+
+ size_t Idx = Str.find('\0');
+ uint64_t N = Idx == StringRef::npos ? UINT64_MAX : Idx + 1;
+ if (Func == LibFunc_strncmp) {
+ if (!isa<ConstantInt>(CI->getArgOperand(2)))
+ return false;
+ N = std::min(N, cast<ConstantInt>(CI->getArgOperand(2))->getZExtValue());
+ }
+ // now N means how many bytes we need to compare at most
+ if (N > Str.size() || N < 2 || N > StrNCmpInlineThreshold)
+ return false;
+
+ Value *StrP = HasStr1 ? Str2P : Str1P;
+
+ // cases that StrP has two or more dereferenceable bytes might be better
+ // optimized elsewhere
+ bool CanBeNull = false, CanBeFreed = false;
+ if (StrP->getPointerDereferenceableBytes(DL, CanBeNull, CanBeFreed) > 1)
+ return false;
+
+ return inlineCompare(StrP, Str, N, HasStr1);
+}
+
+/// Convert
+///
+/// \code
+/// ret = compare(s1, s2, N)
+/// \endcode
+///
+/// into
+///
+/// \code
+/// ret = (int)s1[0] - (int)s2[0]
+/// if (ret != 0)
+/// goto NE
+/// ...
+/// ret = (int)s1[N-2] - (int)s2[N-2]
+/// if (ret != 0)
+/// goto NE
+/// ret = (int)s1[N-1] - (int)s2[N-1]
+/// NE:
+/// \endcode
+///
+/// CFG before and after the transformation:
+///
+/// (before)
+/// BBCI
+///
+/// (after)
+/// BBBefore -> BBSubs[0] (sub,icmp) --NE-> BBNE -> BBCI
+/// | ^
+/// E |
+/// | |
+/// BBSubs[1] (sub,icmp) --NE-----+
+/// ... |
+/// BBSubs[N-1] (sub) ---------+
+///
+bool StrNCmpInliner::inlineCompare(Value *LHS, StringRef RHS, uint64_t N,
+ bool Switched) {
+ IRBuilder<> B(CI->getContext());
+
+ BasicBlock *BBCI = CI->getParent();
+ bool IsEntry = BBCI->isEntryBlock();
+ BasicBlock *BBBefore = splitBlockBefore(BBCI, CI, DTU, nullptr, nullptr,
+ BBCI->getName() + ".before");
+
+ SmallVector<BasicBlock *> BBSubs;
+ for (uint64_t i = 0; i < N + 1; ++i)
+ BBSubs.push_back(
+ BasicBlock::Create(CI->getContext(), "sub", BBCI->getParent(), BBCI));
+ BasicBlock *BBNE = BBSubs[N];
+
+ cast<BranchInst>(BBBefore->getTerminator())->setSuccessor(0, BBSubs[0]);
+
+ B.SetInsertPoint(BBNE);
+ PHINode *Phi = B.CreatePHI(CI->getType(), N);
+ B.CreateBr(BBCI);
+
+ Value *Base = LHS;
+ for (uint64_t i = 0; i < N; ++i) {
+ B.SetInsertPoint(BBSubs[i]);
+ Value *VL = B.CreateZExt(
+ B.CreateLoad(B.getInt8Ty(),
+ B.CreateInBoundsGEP(B.getInt8Ty(), Base, B.getInt64(i))),
+ CI->getType());
+ Value *VR = ConstantInt::get(CI->getType(), RHS[i]);
+ Value *Sub = Switched ? B.CreateSub(VR, VL) : B.CreateSub(VL, VR);
+ if (i < N - 1)
+ B.CreateCondBr(B.CreateICmpNE(Sub, ConstantInt::get(CI->getType(), 0)),
+ BBNE, BBSubs[i + 1]);
+ else
+ B.CreateBr(BBNE);
+
+ Phi->addIncoming(Sub, BBSubs[i]);
+ }
+
+ CI->replaceAllUsesWith(Phi);
+ CI->eraseFromParent();
+
+ BBNext = BBCI->getIterator();
+
+ // Update DomTree
+ if (DTU) {
+ if (IsEntry) {
+ DTU->recalculate(*BBCI->getParent());
+ } else {
+ SmallVector<DominatorTree::UpdateType, 8> Updates;
+ Updates.push_back({DominatorTree::Delete, BBBefore, BBCI});
+ Updates.push_back({DominatorTree::Insert, BBBefore, BBSubs[0]});
+ for (uint64_t i = 0; i < N; ++i) {
+ if (i < N - 1)
+ Updates.push_back({DominatorTree::Insert, BBSubs[i], BBSubs[i + 1]});
+ Updates.push_back({DominatorTree::Insert, BBSubs[i], BBNE});
+ }
+ Updates.push_back({DominatorTree::Insert, BBNE, BBCI});
+ DTU->applyUpdates(Updates);
+ }
+ }
+ return true;
+}
+
+static bool inlineLibCalls(Function &F, TargetLibraryInfo &TLI,
+ const TargetTransformInfo &TTI, DominatorTree &DT,
+ bool &MadeCFGChange) {
+ MadeCFGChange = false;
+ DomTreeUpdater DTU(&DT, DomTreeUpdater::UpdateStrategy::Lazy);
+
+ bool MadeChange = false;
+
+ Function::iterator CurrBB;
+ for (Function::iterator BB = F.begin(), BE = F.end(); BB != BE;) {
+ CurrBB = BB++;
+
+ for (BasicBlock::iterator II = CurrBB->begin(), IE = CurrBB->end();
+ II != IE; ++II) {
+ CallInst *Call = dyn_cast<CallInst>(&*II);
+ Function *CalledFunc;
+
+ if (!Call || !(CalledFunc = Call->getCalledFunction()))
+ continue;
+
+ if (Call->isNoBuiltin())
+ continue;
+
+ // Skip if function either has local linkage or is not a known library
+ // function.
+ LibFunc LF;
+ if (CalledFunc->hasLocalLinkage() || !TLI.getLibFunc(*CalledFunc, LF) ||
+ !TLI.has(LF))
+ continue;
+
+ switch (LF) {
+ case LibFunc_strcmp:
+ case LibFunc_strncmp: {
+ auto &DL = F.getParent()->getDataLayout();
+ if (StrNCmpInliner(Call, LF, BB, &DTU, DL).optimizeStrNCmp()) {
+ MadeCFGChange = true;
+ break;
+ }
+ continue;
+ }
+ default:
+ continue;
+ }
+
+ MadeChange = true;
+ break;
+ }
+ }
+
+ return MadeChange;
+}
+
/// This is the entry point for folds that could be implemented in regular
/// InstCombine, but they are separated because they are not expected to
/// occur frequently and/or have more than a constant-length pattern match.
@@ -969,11 +1216,12 @@ static bool foldUnusualPatterns(Function &F, DominatorTree &DT,
/// handled in the callers of this function.
static bool runImpl(Function &F, AssumptionCache &AC, TargetTransformInfo &TTI,
TargetLibraryInfo &TLI, DominatorTree &DT,
- AliasAnalysis &AA) {
+ AliasAnalysis &AA, bool &MadeCFGChange) {
bool MadeChange = false;
const DataLayout &DL = F.getParent()->getDataLayout();
TruncInstCombine TIC(AC, TLI, DL, DT);
MadeChange |= TIC.run(F);
+ MadeChange |= inlineLibCalls(F, TLI, TTI, DT, MadeCFGChange);
MadeChange |= foldUnusualPatterns(F, DT, TTI, TLI, AA, AC);
return MadeChange;
}
@@ -985,12 +1233,16 @@ PreservedAnalyses AggressiveInstCombinePass::run(Function &F,
auto &DT = AM.getResult<DominatorTreeAnalysis>(F);
auto &TTI = AM.getResult<TargetIRAnalysis>(F);
auto &AA = AM.getResult<AAManager>(F);
- if (!runImpl(F, AC, TTI, TLI, DT, AA)) {
+ bool MadeCFGChange = false;
+ if (!runImpl(F, AC, TTI, TLI, DT, AA, MadeCFGChange)) {
// No changes, all analyses are preserved.
return PreservedAnalyses::all();
}
// Mark all the analyses that instcombine updates as preserved.
PreservedAnalyses PA;
- PA.preserveSet<CFGAnalyses>();
+ if (MadeCFGChange)
+ PA.preserve<DominatorTreeAnalysis>();
+ else
+ PA.preserveSet<CFGAnalyses>();
return PA;
}
diff --git a/llvm/test/Transforms/AggressiveInstCombine/strcmp.ll b/llvm/test/Transforms/AggressiveInstCombine/strcmp.ll
deleted file mode 100644
index 99dd450e6f44e6..00000000000000
--- a/llvm/test/Transforms/AggressiveInstCombine/strcmp.ll
+++ /dev/null
@@ -1,219 +0,0 @@
-; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -passes=aggressive-instcombine -S | FileCheck %s
-
-declare i32 @strcmp(ptr, ptr)
-
-@s0 = constant [1 x i8] c"\00"
-@s1 = constant [2 x i8] c"0\00"
-@s2 = constant [3 x i8] c"01\00"
-@s3 = constant [4 x i8] c"012\00"
-@s4 = constant [5 x i8] c"0123\00"
-
-; Expand strcmp(C, "x"), strcmp(C, "xy").
-
-define i1 @expand_strcmp_s0(ptr %C) {
-; CHECK-LABEL: @expand_strcmp_s0(
-; CHECK-NEXT: [[CALL:%.*]] = call i32 @strcmp(ptr [[C:%.*]], ptr @s0)
-; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[CALL]], 0
-; CHECK-NEXT: ret i1 [[CMP]]
-;
- %call = call i32 @strcmp(ptr %C, ptr @s0)
- %cmp = icmp eq i32 %call, 0
- ret i1 %cmp
-}
-
-define i1 @expand_strcmp_eq_s1(ptr %C) {
-; CHECK-LABEL: @expand_strcmp_eq_s1(
-; CHECK-NEXT: [[CALL:%.*]] = call i32 @strcmp(ptr [[C:%.*]], ptr @s1)
-; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[CALL]], 0
-; CHECK-NEXT: ret i1 [[CMP]]
-;
- %call = call i32 @strcmp(ptr %C, ptr @s1)
- %cmp = icmp eq i32 %call, 0
- ret i1 %cmp
-}
-
-define i1 @expand_strcmp_eq_s1_commuted(ptr %C) {
-; CHECK-LABEL: @expand_strcmp_eq_s1_commuted(
-; CHECK-NEXT: [[CALL:%.*]] = call i32 @strcmp(ptr @s1, ptr [[C:%.*]])
-; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[CALL]], 0
-; CHECK-NEXT: ret i1 [[CMP]]
-;
- %call = call i32 @strcmp(ptr @s1, ptr %C)
- %cmp = icmp eq i32 %call, 0
- ret i1 %cmp
-}
-
-define i1 @expand_strcmp_ne_s1(ptr %C) {
-; CHECK-LABEL: @expand_strcmp_ne_s1(
-; CHECK-NEXT: [[CALL:%.*]] = call i32 @strcmp(ptr [[C:%.*]], ptr @s1)
-; CHECK-NEXT: [[CMP:%.*]] = icmp ne i32 [[CALL]], 0
-; CHECK-NEXT: ret i1 [[CMP]]
-;
- %call = call i32 @strcmp(ptr %C, ptr @s1)
- %cmp = icmp ne i32 %call, 0
- ret i1 %cmp
-}
-
-define i1 @expand_strcmp_sgt_s1(ptr %C) {
-; CHECK-LABEL: @expand_strcmp_sgt_s1(
-; CHECK-NEXT: [[CALL:%.*]] = call i32 @strcmp(ptr [[C:%.*]], ptr @s1)
-; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i32 [[CALL]], 0
-; CHECK-NEXT: ret i1 [[CMP]]
-;
- %call = call i32 @strcmp(ptr %C, ptr @s1)
- %cmp = icmp sgt i32 %call, 0
- ret i1 %cmp
-}
-
-define i1 @expand_strcmp_sge_s1(ptr %C) {
-; CHECK-LABEL: @expand_strcmp_sge_s1(
-; CHECK-NEXT: [[CALL:%.*]] = call i32 @strcmp(ptr [[C:%.*]], ptr @s1)
-; CHECK-NEXT: [[CMP:%.*]] = icmp sge i32 [[CALL]], 0
-; CHECK-NEXT: ret i1 [[CMP]]
-;
- %call = call i32 @strcmp(ptr %C, ptr @s1)
- %cmp = icmp sge i32 %call, 0
- ret i1 %cmp
-}
-
-define i1 @expand_strcmp_slt_s1(ptr %C) {
-; CHECK-LABEL: @expand_strcmp_slt_s1(
-; CHECK-NEXT: [[CALL:%.*]] = call i32 @strcmp(ptr [[C:%.*]], ptr @s1)
-; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[CALL]], 0
-; CHECK-NEXT: ret i1 [[CMP]]
-;
- %call = call i32 @strcmp(ptr %C, ptr @s1)
- %cmp = icmp slt i32 %call, 0
- ret i1 %cmp
-}
-
-define i1 @expand_strcmp_sle_s1(ptr %C) {
-; CHECK-LABEL: @expand_strcmp_sle_s1(
-; CHECK-NEXT: [[CALL:%.*]] = call i32 @strcmp(ptr [[C:%.*]], ptr @s1)
-; CHECK-NEXT: [[CMP:%.*]] = icmp sle i32 [[CALL]], 0
-; CHECK-NEXT: ret i1 [[CMP]]
-;
- %call = call i32 @strcmp(ptr %C, ptr @s1)
- %cmp = icmp sle i32 %call, 0
- ret i1 %cmp
-}
-
-define i1 @expand_strcmp_s1_fail_1(ptr %C) {
-; CHECK-LABEL: @expand_strcmp_s1_fail_1(
-; CHECK-NEXT: [[CALL:%.*]] = call i32 @strcmp(ptr [[C:%.*]], ptr @s1)
-; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[CALL]], 1
-; CHECK-NEXT: ret i1 [[CMP]]
-;
- %call = call i32 @strcmp(ptr %C, ptr @s1)
- %cmp = icmp eq i32 %call, 1
- ret i1 %cmp
-}
-
-define i1 @expand_strcmp_s1_fail_2(ptr %C) {
-; CHECK-LABEL: @expand_strcmp_s1_fail_2(
-; CHECK-NEXT: [[CALL:%.*]] = call i32 @strcmp(ptr @s1, ptr @s1)
-; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[CALL]], 0
-; CHECK-NEXT: ret i1 [[CMP]]
-;
- %call = call i32 @strcmp(ptr @s1, ptr @s1)
- %cmp = icmp eq i32 %call, 0
- ret i1 %cmp
-}
-
-define i32 @expand_strcmp_s1_fail_3(ptr %C) {
-; CHECK-LABEL: @expand_strcmp_s1_fail_3(
-; CHECK-NEXT: [[CALL:%.*]] = call i32 @strcmp(ptr [[C:%.*]], ptr @s1)
-; CHECK-NEXT: ret i32 [[CALL]]
-;
- %call = call i32 @strcmp(ptr %C, ptr @s1)
- ret i32 %call
-}
-
-define i1 @expand_strcmp_eq_s2(ptr %C) {
-; CHECK-LABEL: @expand_strcmp_eq_s2(
-; CHECK-NEXT: [[CALL:%.*]] = call i32 @strcmp(ptr [[C:%.*]], ptr @s2)
-; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[CALL]], 0
-; CHECK-NEXT: ret i1 [[CMP]]
-;
- %call = call i32 @strcmp(ptr %C, ptr @s2)
- %cmp = icmp eq i32 %call, 0
- ret i1 %cmp
-}
-
-define i1 @expand_strcmp_ne_s2(ptr %C) {
-; CHECK-LABEL: @expand_strcmp_ne_s2(
-; CHECK-NEXT: [[CALL:%.*]] = call i32 @strcmp(ptr [[C:%.*]], ptr @s2)
-; CHECK-NEXT: [[CMP:%.*]] = icmp ne i32 [[CALL]], 0
-; CHECK-NEXT: ret i1 [[CMP]]
-;
- %call = call i32 @strcmp(ptr %C, ptr @s2)
- %cmp = icmp ne i32 %call, 0
- ret i1 %cmp
-}
-
-define i1 @expand_strcmp_sgt_s2(ptr %C) {
-; CHECK-LABEL: @expand_strcmp_sgt_s2(
-; CHECK-NEXT: [[CALL:%.*]] = call i32 @strcmp(ptr [[C:%.*]], ptr @s2)
-; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i32 [[CALL]], 0
-; CHECK-NEXT: ret i1 [[CMP]]
-;
- %call = call i32 @strcmp(ptr %C, ptr @s2)
- %cmp = icmp sgt i32 %call, 0
- ret i1 %cmp
-}
-
-define i1 @expand_strcmp_sge_s2(ptr %C) {
-; CHECK-LABEL: @expand_strcmp_sge_s2(
-; CHECK-NEXT: [[CALL:%.*]] = call i32 @strcmp(ptr [[C:%.*]], ptr @s2)
-; CHECK-NEXT: [[CMP:%.*]] = icmp sge i32 [[CALL]], 0
-; CHECK-NEXT: ret i1 [[CMP]]
-;
- %call = call i32 @strcmp(ptr %C, ptr @s2)
- %cmp = icmp sge i32 %call, 0
- ret i1 %cmp
-}
-
-define i1 @expand_strcmp_slt_s2(ptr %C) {
-; CHECK-LABEL: @expand_strcmp_slt_s2(
-; CHECK-NEXT: [[CALL:%.*]] = call i32 @strcmp(ptr [[C:%.*]], ptr @s2)
-; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[CALL]], 0
-; CHECK-NEXT: ret i1 [[CMP]]
-;
- %call = call i32 @strcmp(ptr %C, ptr @s2)
- %cmp = icmp slt i32 %call, 0
- ret i1 %cmp
-}
-
-define i1 @expand_strcmp_sle_s2(ptr %C) {
-; CHECK-LABEL: @expand_strcmp_sle_s2(
-; CHECK-NEXT: [[CALL:%.*]] = call i32 @strcmp(ptr [[C:%.*]], ptr @s2)
-; CHECK-NEXT: [[CMP:%.*]] = icmp sle i32 [[CALL]], 0
-; CHECK-NEXT: ret i1 [[CMP]]
-;
- %call = call i32 @strcmp(ptr %C, ptr @s2)
- %cmp = icmp sle i32 %call, 0
- ret i1 %cmp
-}
-
-define i1 @expand_strcmp_s3(ptr %C) {
-; CHECK-LABEL: @expand_strcmp_s3(
-; CHECK-NEXT: [[CALL:%.*]] = call i32 @strcmp(ptr [[C:%.*]], ptr @s3)
-; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[CALL]], 0
-; CHECK-NEXT: ret i1 [[CMP]]
-;
- %call = call i32 @strcmp(ptr %C, ptr @s3)
- %cmp = icmp eq i32 %call, 0
- ret i1 %cmp
-}
-
-define i1 @expand_strcmp_s4(ptr %C) {
-; CHECK-LABEL: @expand_strcmp_s4(
-; CHECK-NEXT: [[CALL:%.*]] = call i32 @strcmp(ptr [[C:%.*]], ptr @s4)
-; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[CALL]], 0
-; CHECK-NEXT: ret i1 [[CMP]]
-;
- %call = call i32 @strcmp(ptr %C, ptr @s4)
- %cmp = icmp eq i32 %call, 0
- ret i1 %cmp
-}
diff --git a/llvm/test/Transforms/AggressiveInstCombine/strncmp-1.ll b/llvm/test/Transforms/AggressiveInstCombine/strncmp-1.ll
new file mode 100644
index 00000000000000..4679d6d7fca143
--- /dev/null
+++ b/llvm/test/Transforms/AggressiveInstCombine/strncmp-1.ll
@@ -0,0 +1,203 @@
+; RUN: opt -S -passes=aggressive-instcombine -strncmp-inline-threshold=3 < %s | FileCheck %s
+
+declare i32 @strncmp(ptr nocapture, ptr nocapture, i64)
+declare i32 @strcmp(ptr nocapture, ptr nocapture)
+
+@.str = private unnamed_addr constant [3 x i8] c"ab\00", align 1
+@.str.1 = private unnamed_addr constant [2 x i8] c"a\00", align 1
+
+define i32 @test_strncmp_1(ptr nocapture readonly %s) {
+; CHECK-LABEL: @test_strncmp_1(
+; CHECK-NEXT: entry.before:
+; CHECK-NEXT: br label [[SUB:%.*]]
+; CHECK: sub:
+; CHECK-NEXT: [[TMP0:%.*]] = getelementptr inbounds i8, ptr [[S:%.*]], i64 0
+; CHECK-NEXT: [[TMP1:%.*]] = load i8, ptr [[TMP0]], align 1
+; CHECK-NEXT: [[TMP2:%.*]] = zext i8 [[TMP1]] to i32
+; CHECK-NEXT: [[TMP3:%.*]] = sub i32 97, [[TMP2]]
+; CHECK-NEXT: [[TMP4:%.*]] = icmp ne i32 [[TMP3]], 0
+; CHECK-NEXT: br i1 [[TMP4]], label [[SUB2:%.*]], label [[SUB1:%.*]]
+; CHECK: sub1:
+; CHECK-NEXT: [[TMP5:%.*]] = getelementptr inbounds i8, ptr [[S]], i64 1
+; CHECK-NEXT: [[TMP6:%.*]] = load i8, ptr [[TMP5]], align 1
+; CHECK-NEXT: [[TMP7:%.*]] = zext i8 [[TMP6]] to i32
+; CHECK-NEXT: [[TMP8:%.*]] = sub i32 98, [[TMP7]]
+; CHECK-NEXT: br label [[SUB2]]
+; CHECK: sub2:
+; CHECK-NEXT: [[TMP9:%.*]] = phi i32 [ [[TMP3]], [[SUB]] ], [ [[TMP8]], [[SUB1]] ]
+; CHECK-NEXT: br label [[ENTRY:%.*]]
+; CHECK: entry:
+; CHECK-NEXT: ret i32 [[TMP9]]
+;
+entry:
+ %call = tail call i32 @strncmp(ptr nonnull dereferenceable(3) @.str, ptr nonnull dereferenceable(1) %s, i64 2)
+ ret i32 %call
+}
+
+define i32 @test_strncmp_2(ptr nocapture readonly %s) {
+; CHECK-LABEL: @test_strncmp_2(
+; CHECK-NEXT: entry.before:
+; CHECK-NEXT: br label [[SUB:%.*]]
+; CHECK: sub:
+; CHECK-NEXT: [[TMP0:%.*]] = getelementptr inbounds i8, ptr [[S:%.*]], i64 0
+; CHECK-NEXT: [[TMP1:%.*]] = load i8, ptr [[TMP0]], align 1
+; CHECK-NEXT: [[TMP2:%.*]] = zext i8 [[TMP1]] to i32
+; CHECK-NEXT: [[TMP3:%.*]] = sub i32 97, [[TMP2]]
+; CHECK-NEXT: [[TMP4:%.*]] = icmp ne i32 [[TMP3]], 0
+; CHECK-NEXT: br i1 [[TMP4]], label [[SUB3:%.*]], label [[SUB1:%.*]]
+; CHECK: sub1:
+; CHECK-NEXT: [[TMP5:%.*]] = getelementptr inbounds i8, ptr [[S]], i64 1
+; CHECK-NEXT: [[TMP6:%.*]] = load i8, ptr [[TMP5]], align 1
+; CHECK-NEXT: [[TMP7:%.*]] = zext i8 [[TMP6]] to i32
+; CHECK-NEXT: [[TMP8:%.*]] = sub i32 98, [[TMP7]]
+; CHECK-NEXT: [[TMP9:%.*]] = icmp ne i32 [[TMP8]], 0
+; CHECK-NEXT: br i1 [[TMP9]], label [[SUB3]], label [[SUB2:%.*]]
+; CHECK: sub2:
+; CHECK-NEXT: [[TMP10:%.*]] = getelementptr inbounds i8, ptr [[S]], i64 2
+; CHECK-NEXT: [[TMP11:%.*]] = load i8, ptr [[TMP10]], align 1
+; CHECK-NEXT: [[TMP12:%.*]] = zext i8 [[TMP11]] to i32
+; CHECK-NEXT: [[TMP13:%.*]] = sub i32 0, [[TMP12]]
+; CHECK-NEXT: br label [[SUB3]]
+; CHECK: sub3:
+; CHECK-NEXT: [[TMP14:%.*]] = phi i32 [ [[TMP3]], [[SUB]] ], [ [[TMP8]], [[SUB1]] ], [ ...
[truncated]
|
dtcxzyw
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* add missing test cases * remove redundant code
goldsteinn
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It looks like this patch crashes when compiling lencod from llvm-test-suite in ReleaseLTO-g configuration: https://llvm-compile-time-tracker.com/show_error.php?commit=73bf9d626bf3fb7a43453f6731f1aecab83177b4 |
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It seems to be a bug related to the new DebugInfo, I found the change as below could fix it. --- a/llvm/lib/IR/BasicBlock.cpp
+++ b/llvm/lib/IR/BasicBlock.cpp
@@ -1009,7 +1009,7 @@ void BasicBlock::spliceDebugInfoImpl(BasicBlock::iterator Dest, BasicBlock *Src,
// generate the iterator with begin() / getFirstInsertionPt(), it means
// any trailing debug-info at the end of the block would "normally" have
// been pushed in front of "First". Move it there now.
- DbgMarker *FirstMarker = getMarker(First);
+ DbgMarker *FirstMarker = createMarker(First);
DbgMarker *TrailingDbgRecords = getTrailingDbgRecords();
if (TrailingDbgRecords) {
FirstMarker->absorbDebugValues(*TrailingDbgRecords, true);I am preparing a minimal test case and will create a new pull request to fix this bug soon. |
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Shoule have been fixed by #90312 |
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✅ With the latest revision this PR passed the C/C++ code formatter. |
* isOnlyUsedInZeroComparison * more tests * ...
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Looks like there is a hang while building the stage 2 compiler now: https://llvm-compile-time-tracker.com/show_error.php?commit=c690fb9bf301e84b21a239dfafb278bab262a762 |
I should have known what is wrong. How can I run these tests before I push the fix? |
I'd recommend you try and reproduce this locally, which you'll need to investigate. To do that, you need to do a 2 stage build
|
* use SplitBlock rather than splitBlockBefore to avoid invalidating the Instruction iterator
Should have been fixed by latest commit 4ca7ba9. Tested by doing a two stage build locally. |
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* improve tests
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| ; CHECK-NEXT: [[TMP8:%.*]] = icmp ne i32 [[TMP7]], 0 | ||
| ; CHECK-NEXT: br i1 [[TMP8]], label [[NE]], label [[SUB2:%.*]] | ||
| ; CHECK: sub_2: | ||
| ; CHECK-NEXT: [[TMP9:%.*]] = getelementptr inbounds i8, ptr [[S]], i64 2 |
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is the inbounds on %s valid here?
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I think so, otherwise the strncmp call would be UB.
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yeah I guess, was thinking we only have derefeanceable(1) on %s, but the entire transform is premised on standard definition of strncmp so you're right.
* improve tests
|
This caused a miscompile in ffmpeg for x86 platforms. It's reproducible on both Linux and MinGW, for both i686 and x86_64. To reproduce on linux on x86: $ git clone https://github.com/ffmpeg/ffmpeg
$ mkdir ffmpeg-build
$ cd ffmpeg-build
$ ../ffmpeg/configure --cc=clang --samples=$(pwd)/../samples
$ make fate-rsync # download test samples
$ make -j$(nproc) fate-subtitlesThe miscompilation lies in the object file I presume we should revert this until the issue has been resolved? |
I'll check this issue soon. This optimization could be disabled by specifying "-mllvm -strncmp-inline-threshold=0" and/or "-Wl,-mllvm,-strncmp-inline-threshold=0". |
|
Hmm, did you remove the message about you being unable to reproduce the issue, or is github glitching? Anyway, I re-reproduced the issue, with clang at d70267f as in your case. To simplify the reproducing and get rid of some potential variables, you can grab https://martin.st/temp/subtitles-preproc.c, compile it with |
|
Sorry, I thought the issue was a compilation error. Then I realized it was about test failures. Yes, I can reproduce it. |
|
I should have known what is wrong, and will push the fix soon. |
|
Should have been fixed by #91204. |
Thanks! I can confirm that the issue is gone now, in all of my regularly tested setups. |
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Inline calls to strcmp(s1, s2) and strncmp(s1, s2, N), where N and exactly one of s1 and s2 are constant.
For example:
is converted to
Ported from a similar gcc feature Inline strcmp with small constant strings.