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[MemoryLocation] Teach MemoryLocation about llvm.experimental.memset.pattern #120421

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Merged
merged 6 commits into from
Jan 15, 2025
Merged

[MemoryLocation] Teach MemoryLocation about llvm.experimental.memset.pattern #120421

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ae5084c
[test] Pre-commit llvm.experimental.memset.pattern tests prior to Mem…
asb Dec 18, 2024
f3a5543
[MemoryLocation] Teach MemoryLocation about llvm.experimental.memset.…
asb Dec 18, 2024
7f16bb1
Address review comment
asb Dec 18, 2024
04a31ee
Merge remote-tracking branch 'origin/main' into 2024q4-memset-pattern…
asb Jan 15, 2025
e2e8509
Add test showing a store being eliminated
asb Jan 15, 2025
14b0347
Merge remote-tracking branch 'origin/main' into 2024q4-memset-pattern…
asb Jan 15, 2025
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12 changes: 12 additions & 0 deletions llvm/lib/Analysis/MemoryLocation.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -183,6 +183,18 @@ MemoryLocation MemoryLocation::getForArgument(const CallBase *Call,
AATags);
return MemoryLocation::getAfter(Arg, AATags);

case Intrinsic::experimental_memset_pattern:
assert((ArgIdx == 0 || ArgIdx == 1) &&
"Invalid argument index for memory intrinsic");
if (ConstantInt *LenCI = dyn_cast<ConstantInt>(II->getArgOperand(2)))
return MemoryLocation(
Arg,
LocationSize::precise(
LenCI->getZExtValue() *
DL.getTypeAllocSize(II->getArgOperand(1)->getType())),
AATags);
return MemoryLocation::getAfter(Arg, AATags);

case Intrinsic::lifetime_start:
case Intrinsic::lifetime_end:
case Intrinsic::invariant_start:
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18 changes: 18 additions & 0 deletions llvm/test/Analysis/BasicAA/memset-pattern.ll
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Original file line number Diff line number Diff line change
@@ -0,0 +1,18 @@
; RUN: opt -mtriple=x86_64 -aa-pipeline=basic-aa -passes=inferattrs,aa-eval -print-all-alias-modref-info -disable-output 2>&1 %s | FileCheck %s

define void @test_memset_pattern4_const_size(ptr noalias %a, i32 %pattern) {
; CHECK-LABEL: Function: test_memset_pattern4_const_size
; CHECK: Just Mod: Ptr: i8* %a <-> call void @llvm.experimental.memset.pattern.p0.i32.i64(ptr %a, i32 %pattern, i64 17, i1 false)
; CHECK-NEXT: Just Mod: Ptr: i8* %a.gep.1 <-> call void @llvm.experimental.memset.pattern.p0.i32.i64(ptr %a, i32 %pattern, i64 17, i1 false)
; CHECK-NEXT: NoModRef: Ptr: i8* %a.gep.129 <-> call void @llvm.experimental.memset.pattern.p0.i32.i64(ptr %a, i32 %pattern, i64 17, i1 false)

entry:
load i8, ptr %a
call void @llvm.experimental.memset.pattern(ptr %a, i32 %pattern, i64 17, i1 0)
%a.gep.1 = getelementptr i8, ptr %a, i32 1
store i8 0, ptr %a.gep.1
%a.gep.129 = getelementptr i8, ptr %a, i32 129
store i8 1, ptr %a.gep.129

ret void
}
65 changes: 65 additions & 0 deletions llvm/test/Transforms/DeadStoreElimination/memory-intrinsics-sizes.ll
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Expand Up @@ -66,6 +66,71 @@ define void @memset_and_store_2(ptr %ptr, i64 %len) {
ret void
}

define void @memset_pattern_equal_size_values(ptr %ptr, i64 %len) {
; CHECK-LABEL: @memset_pattern_equal_size_values(
; CHECK-NEXT: call void @llvm.experimental.memset.pattern.p0.i8.i64(ptr align 1 [[PTR:%.*]], i8 0, i64 [[LEN:%.*]], i1 false)
; CHECK-NEXT: ret void
;
call void @llvm.experimental.memset.pattern.p0.i8.i64(ptr align 1 %ptr, i8 0, i64 %len, i1 false)
call void @llvm.experimental.memset.pattern.p0.i8.i64(ptr align 1 %ptr, i8 0, i64 %len, i1 false)
ret void
}

define void @memset_pattern_different_size_values_1(ptr %ptr, i64 %len.1, i64 %len.2) {
; CHECK-LABEL: @memset_pattern_different_size_values_1(
; CHECK-NEXT: call void @llvm.experimental.memset.pattern.p0.i8.i64(ptr align 1 [[PTR:%.*]], i8 0, i64 [[LEN_1:%.*]], i1 false)
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A general enhancement we could do for this case would be to fold the calls to a length which is the umin of the two lengths. This is generic and not related to this change.

; CHECK-NEXT: call void @llvm.experimental.memset.pattern.p0.i8.i64(ptr align 1 [[PTR]], i8 0, i64 [[LEN_2:%.*]], i1 false)
; CHECK-NEXT: ret void
;
call void @llvm.experimental.memset.pattern.p0.i8.i64(ptr align 1 %ptr, i8 0, i64 %len.1, i1 false)
call void @llvm.experimental.memset.pattern.p0.i8.i64(ptr align 1 %ptr, i8 0, i64 %len.2, i1 false)
ret void
}

define void @memset_pattern_different_size_values_2(ptr %ptr, i64 %len) {
; CHECK-LABEL: @memset_pattern_different_size_values_2(
; CHECK-NEXT: call void @llvm.experimental.memset.pattern.p0.i8.i64(ptr align 1 [[PTR:%.*]], i8 0, i64 [[LEN:%.*]], i1 false)
; CHECK-NEXT: call void @llvm.experimental.memset.pattern.p0.i8.i64(ptr align 1 [[PTR]], i8 0, i64 100, i1 false)
; CHECK-NEXT: ret void
;
call void @llvm.experimental.memset.pattern.p0.i8.i64(ptr align 1 %ptr, i8 0, i64 %len, i1 false)
call void @llvm.experimental.memset.pattern.p0.i8.i64(ptr align 1 %ptr, i8 0, i64 100, i1 false)
ret void
}

define void @memset_pattern_different_size_values_3(ptr %ptr, i64 %len) {
; CHECK-LABEL: @memset_pattern_different_size_values_3(
; CHECK-NEXT: call void @llvm.experimental.memset.pattern.p0.i8.i64(ptr align 1 [[PTR:%.*]], i8 0, i64 100, i1 false)
; CHECK-NEXT: call void @llvm.experimental.memset.pattern.p0.i8.i64(ptr align 1 [[PTR]], i8 0, i64 [[LEN:%.*]], i1 false)
; CHECK-NEXT: ret void
;
call void @llvm.experimental.memset.pattern.p0.i8.i64(ptr align 1 %ptr, i8 0, i64 100, i1 false)
call void @llvm.experimental.memset.pattern.p0.i8.i64(ptr align 1 %ptr, i8 0, i64 %len, i1 false)
ret void
}

define void @memset_pattern_and_store_1(ptr %ptr, i64 %len) {
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Can you add a positive test? One which shows we can eliminate the store if the length is a constant?

; CHECK-LABEL: @memset_pattern_and_store_1(
; CHECK-NEXT: store i64 123, ptr [[PTR:%.*]], align 4
; CHECK-NEXT: call void @llvm.experimental.memset.pattern.p0.i8.i64(ptr align 1 [[PTR]], i8 0, i64 [[LEN:%.*]], i1 false)
; CHECK-NEXT: ret void
;
store i64 123, ptr %ptr
call void @llvm.experimental.memset.pattern.p0.i8.i64(ptr align 1 %ptr, i8 0, i64 %len, i1 false)
ret void
}

define void @memset_pattern_and_store_2(ptr %ptr, i64 %len) {
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Possibly generic - but if we have a constant length, we could offset the start of the call and subtract 8 from length since we know the store follows.

; CHECK-LABEL: @memset_pattern_and_store_2(
; CHECK-NEXT: call void @llvm.experimental.memset.pattern.p0.i8.i64(ptr align 1 [[PTR:%.*]], i8 0, i64 [[LEN:%.*]], i1 false)
; CHECK-NEXT: store i64 123, ptr [[PTR]], align 4
; CHECK-NEXT: ret void
;
call void @llvm.experimental.memset.pattern.p0.i8.i64(ptr align 1 %ptr, i8 0, i64 %len, i1 false)
store i64 123, ptr %ptr
ret void
}

define void @memcpy_equal_size_values(ptr noalias %src, ptr noalias %dst, i64 %len) {
; CHECK-LABEL: @memcpy_equal_size_values(
; CHECK-NEXT: call void @llvm.memcpy.p0.p0.i64(ptr [[DST:%.*]], ptr [[SRC:%.*]], i64 [[LEN:%.*]], i1 false)
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