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[BOLT] Improve BinaryFunction::inferFallThroughCounts() #105450

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Merged
merged 4 commits into from
Aug 21, 2024
Merged

[BOLT] Improve BinaryFunction::inferFallThroughCounts() #105450

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e903d5f
[BOLT] Improve BinaryFunction::inferFallThroughCounts()
ShatianWang Aug 20, 2024
14564bf
fixup! [BOLT] Improve BinaryFunction::inferFallThroughCounts()
ShatianWang Aug 21, 2024
4af894a
fixup! fixup! [BOLT] Improve BinaryFunction::inferFallThroughCounts()
ShatianWang Aug 21, 2024
d2f507a
fixup! fixup! fixup! [BOLT] Improve BinaryFunction::inferFallThroughC…
ShatianWang Aug 21, 2024
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3 changes: 2 additions & 1 deletion bolt/lib/Core/BinaryFunctionProfile.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -336,7 +336,8 @@ void BinaryFunction::inferFallThroughCounts() {
if (SuccBI.Count == 0) {
SuccBI.Count = Inferred;
SuccBI.MispredictedCount = BinaryBasicBlock::COUNT_INFERRED;
Succ->ExecutionCount += Inferred;
Succ->ExecutionCount =
std::max(Succ->getKnownExecutionCount(), Inferred);
}
}
}
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45 changes: 45 additions & 0 deletions bolt/test/X86/infer-fall-throughs.s
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@@ -0,0 +1,45 @@
## Test that infer-fall-throughs would correctly infer the wrong fall-through
## edge count in the example

# RUN: llvm-mc --filetype=obj --triple x86_64-unknown-unknown %s -o %t.o
# RUN: link_fdata %s %t.o %t.fdata
# RUN: llvm-strip --strip-unneeded %t.o
# RUN: %clang %cflags %t.o -o %t.exe -Wl,-q
# RUN: llvm-bolt %t.exe -o %t.bolt \
# RUN: --print-estimate-edge-counts --data=%t.fdata \
# RUN: 2>&1 | FileCheck --check-prefix=WITHOUTINFERENCE %s
# RUN: llvm-bolt %t.exe -o %t.bolt --infer-fall-throughs \
# RUN: --print-estimate-edge-counts --data=%t.fdata \
# RUN: 2>&1 | FileCheck --check-prefix=CORRECTINFERENCE %s


# WITHOUTINFERENCE: Binary Function "main" after estimate-edge-counts
# WITHOUTINFERENCE: {{^\.Ltmp0}}
# WITHOUTINFERENCE: Successors: .Ltmp1 (mispreds: 0, count: 10), .LFT0 (mispreds: 0, count: 0)
# WITHOUTINFERENCE: {{^\.LFT0}}
# WITHOUTINFERENCE: Exec Count : 490

# CORRECTINFERENCE: Binary Function "main" after estimate-edge-counts
# CORRECTINFERENCE: {{^\.Ltmp0}}
# CORRECTINFERENCE: Successors: .Ltmp1 (mispreds: 0, count: 10), .LFT0 (inferred count: 490)
# CORRECTINFERENCE: {{^\.LFT0}}
# CORRECTINFERENCE: Exec Count : 490


.globl main
.type main, @function
main:
LLmain_LLstart:
jmp LLstart
# FDATA: 1 main #LLmain_LLstart# 1 main #LLstart# 0 500
LLstart:
jge LLexit
# FDATA: 1 main #LLstart# 1 main #LLexit# 0 10
# FDATA: 1 main #LLstart# 1 main #LLmore# 0 0
LLmore:
movl $5, %eax
# FDATA: 1 main #LLmore# 1 main #LLexit# 0 490
LLexit:
ret
.LLmain_end:
.size main, .LLmain_end-main
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