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[BOLT] Allow pass-through blocks in YAMLProfileReader #92046
[BOLT] Allow pass-through blocks in YAMLProfileReader #92046
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Created using spr 1.3.4
@llvm/pr-subscribers-bolt Author: Amir Ayupov (aaupov) ChangesAlign YAMLProfileReader with DataReader in handling non-matching edges. ccb99dd introduced a compatibility A similar case arises when profiling BOLTed binaries with block B Test Plan: Added profile-passthrough-block.test Full diff: https://github.com/llvm/llvm-project/pull/92046.diff 3 Files Affected:
diff --git a/bolt/lib/Profile/DataReader.cpp b/bolt/lib/Profile/DataReader.cpp
index b2511ba103998..470a552bae078 100644
--- a/bolt/lib/Profile/DataReader.cpp
+++ b/bolt/lib/Profile/DataReader.cpp
@@ -775,6 +775,9 @@ bool DataReader::recordBranch(BinaryFunction &BF, uint64_t From, uint64_t To,
if (collectedInBoltedBinary() && FromBB == ToBB)
return true;
+ // Allow passthrough blocks.
+ // If this backwards compatibility is dropped, remove equivalent handling
+ // in YAMLProfileReader::parseFunctionProfile.
BinaryBasicBlock *FTSuccessor = FromBB->getConditionalSuccessor(false);
if (FTSuccessor && FTSuccessor->succ_size() == 1 &&
FTSuccessor->getSuccessor(ToBB->getLabel())) {
diff --git a/bolt/lib/Profile/YAMLProfileReader.cpp b/bolt/lib/Profile/YAMLProfileReader.cpp
index e4673f6e3c301..0c262833d2ecc 100644
--- a/bolt/lib/Profile/YAMLProfileReader.cpp
+++ b/bolt/lib/Profile/YAMLProfileReader.cpp
@@ -218,17 +218,32 @@ bool YAMLProfileReader::parseFunctionProfile(
continue;
}
- BinaryBasicBlock &SuccessorBB = *Order[YamlSI.Index];
- if (!BB.getSuccessor(SuccessorBB.getLabel())) {
- if (opts::Verbosity >= 1)
- errs() << "BOLT-WARNING: no successor for block " << BB.getName()
- << " that matches index " << YamlSI.Index << " or block "
- << SuccessorBB.getName() << '\n';
- ++MismatchedEdges;
- continue;
+ BinaryBasicBlock *ToBB = Order[YamlSI.Index];
+ if (!BB.getSuccessor(ToBB->getLabel())) {
+ // Allow passthrough blocks. DataReader supports that as backwards
+ // compatibility feature, which affects BAT fdata parsing wrt
+ // BOLT-removed blocks. Introduce equivalent handling to align with BAT
+ // fdata reader. If the support is dropped in DataReader::recordBranch,
+ // remove this handling in sync.
+ BinaryBasicBlock *FTSuccessor = BB.getConditionalSuccessor(false);
+ if (FTSuccessor && FTSuccessor->succ_size() == 1 &&
+ FTSuccessor->getSuccessor(ToBB->getLabel())) {
+ BinaryBasicBlock::BinaryBranchInfo &FTBI =
+ FTSuccessor->getBranchInfo(*ToBB);
+ FTBI.Count += YamlSI.Count;
+ FTBI.MispredictedCount += YamlSI.Mispreds;
+ ToBB = FTSuccessor;
+ } else {
+ if (opts::Verbosity >= 1)
+ errs() << "BOLT-WARNING: no successor for block " << BB.getName()
+ << " that matches index " << YamlSI.Index << " or block "
+ << ToBB->getName() << '\n';
+ ++MismatchedEdges;
+ continue;
+ }
}
- BinaryBasicBlock::BinaryBranchInfo &BI = BB.getBranchInfo(SuccessorBB);
+ BinaryBasicBlock::BinaryBranchInfo &BI = BB.getBranchInfo(*ToBB);
BI.Count += YamlSI.Count;
BI.MispredictedCount += YamlSI.Mispreds;
}
diff --git a/bolt/test/X86/profile-passthrough-block.test b/bolt/test/X86/profile-passthrough-block.test
new file mode 100644
index 0000000000000..2f6a4ac329677
--- /dev/null
+++ b/bolt/test/X86/profile-passthrough-block.test
@@ -0,0 +1,66 @@
+## Test YAMLProfileReader support for pass-through blocks in non-matching edges:
+## match the profile edge A -> C to the CFG with blocks A -> B -> C.
+
+# REQUIRES: system-linux
+# RUN: split-file %s %t
+# RUN: llvm-mc -filetype=obj -triple x86_64-unknown-unknown %t/main.s -o %t.o
+# RUN: %clang %cflags %t.o -o %t.exe -Wl,-q -nostdlib
+# RUN: llvm-bolt %t.exe -o %t.out --data %t/yaml --profile-ignore-hash -v=1 \
+# RUN: 2>&1 | FileCheck %s
+
+# CHECK: BOLT-INFO: 1 out of 1 functions in the binary (100.0%) have non-empty execution profile
+# CHECK-NOT: BOLT-WARNING: no successor for block .LFT0 that matches index 3 or block .Ltmp0
+
+#--- main.s
+.globl main
+.type main, @function
+main:
+ .cfi_startproc
+.LBB00:
+ pushq %rbp
+ movq %rsp, %rbp
+ subq $16, %rsp
+ testq %rax, %rax
+ js .LBB03
+.LBB01:
+ jne .LBB04
+.LBB02:
+ nop
+.LBB03:
+ xorl %eax, %eax
+ addq $16, %rsp
+ popq %rbp
+ retq
+.LBB04:
+ xorl %eax, %eax
+ addq $16, %rsp
+ popq %rbp
+ retq
+## For relocations against .text
+.LBB05:
+ call exit
+ .cfi_endproc
+ .size main, .-main
+
+#--- yaml
+---
+header:
+ profile-version: 1
+ binary-name: 'profile-passthrough-block.s.tmp.exe'
+ binary-build-id: '<unknown>'
+ profile-flags: [ lbr ]
+ profile-origin: branch profile reader
+ profile-events: ''
+ dfs-order: false
+ hash-func: xxh3
+functions:
+ - name: main
+ fid: 0
+ hash: 0x0000000000000000
+ exec: 1
+ nblocks: 6
+ blocks:
+ - bid: 1
+ insns: 1
+ succ: [ { bid: 3, cnt: 1} ]
+...
|
Align YAMLProfileReader with DataReader in handling non-matching edges.
ccb99dd introduced a compatibility
feature to allow pass-through blocks in non-matching edges:
match the profile edge A -> C to the CFG with blocks A -> B -> C.
A similar case arises when profiling BOLTed binaries with block B
removed.
Test Plan: Added profile-passthrough-block.test