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[BOLT] Preserve Offset annotation in SCTC #91693

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Merged
merged 4 commits into from
May 10, 2024
Merged

[BOLT] Preserve Offset annotation in SCTC #91693

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2ec259b
[BOLT] Preserve Offset annotation in SCTC
aaupov May 10, 2024
0bc277d
Address comments
aaupov May 10, 2024
8fdd3a0
Update test description
aaupov May 10, 2024
b97206e
Update test
aaupov May 10, 2024
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5 changes: 5 additions & 0 deletions bolt/lib/Passes/BinaryPasses.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -910,6 +910,11 @@ uint64_t SimplifyConditionalTailCalls::fixTailCalls(BinaryFunction &BF) {
auto &CTCAnnotation =
MIB->getOrCreateAnnotationAs<uint64_t>(*CondBranch, "CTCTakenCount");
CTCAnnotation = CTCTakenFreq;
// Preserve Offset annotation, used in BAT.
// Instr is a direct tail call instruction that was created when CTCs are
// first expanded, and has the original CTC offset set.
if (std::optional<uint32_t> Offset = MIB->getOffset(*Instr))
MIB->setOffset(*CondBranch, *Offset);

// Remove the unused successor which may be eliminated later
// if there are no other users.
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10 changes: 7 additions & 3 deletions bolt/test/X86/sctc-bug4.test
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@@ -1,25 +1,29 @@
# Check that fallthrough blocks are handled properly.
# Check that fallthrough blocks are handled properly and Offset annotation is
# set for conditional tail calls.

RUN: %clang %cflags %S/Inputs/sctc_bug4.s -o %t
RUN: llvm-bolt %t -o %t.null \
RUN: llvm-bolt %t -o %t.null --enable-bat \
RUN: -funcs=test_func -print-sctc -sequential-disassembly 2>&1 | FileCheck %s

CHECK: .Ltmp2 (3 instructions, align : 1)
CHECK-NEXT: CFI State : 0
CHECK-NEXT: Input offset: 0x24
CHECK-NEXT: Predecessors: .LFT1
CHECK-NEXT: 00000024: cmpq $0x20, %rsi
CHECK-NEXT: 00000028: ja dummy # TAILCALL {{.*}}# CTCTakenCount: 0
CHECK-NEXT: 00000028: ja dummy # TAILCALL # Offset: 53 # CTCTakenCount: 0
CHECK-NEXT: 0000002a: jmp .Ltmp4
CHECK-NEXT: Successors: .Ltmp4
CHECK-NEXT: CFI State: 0

CHECK: .Ltmp1 (2 instructions, align : 1)
CHECK-NEXT: CFI State : 0
CHECK-NEXT: Input offset: 0x2c
CHECK-NEXT: Predecessors: .LFT0
CHECK-NEXT: 0000002c: xorq %r11, %rax
CHECK-NEXT: 0000002f: retq
CHECK-NEXT: CFI State: 0

CHECK: .Ltmp4 (4 instructions, align : 1)
CHECK-NEXT: CFI State : 0
CHECK-NEXT: Input offset: 0x3a
CHECK-NEXT: Predecessors: .Ltmp2
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