[llvm-branch-commits] [llvm] [Metadata] Preserve MD_prof when merging instructions when one is missing. (PR #132433)
Snehasish Kumar via llvm-branch-commits
llvm-branch-commits at lists.llvm.org
Sun Mar 30 13:56:53 PDT 2025
https://github.com/snehasish updated https://github.com/llvm/llvm-project/pull/132433
>From 42a9972571f8c8872e7d71def2236be400428606 Mon Sep 17 00:00:00 2001
From: Snehasish Kumar <snehasishk at google.com>
Date: Fri, 21 Mar 2025 17:00:38 +0000
Subject: [PATCH] Update tests, apply clang-tidy suggestions
---
llvm/lib/Transforms/Utils/Local.cpp | 19 ++++--
...rect-call-branch-weights-preserve-hoist.ll | 62 ++++++++++++++++++
...irect-call-branch-weights-preserve-sink.ll | 63 +++++++++++++++++++
3 files changed, 138 insertions(+), 6 deletions(-)
create mode 100644 llvm/test/Transforms/SimplifyCFG/merge-direct-call-branch-weights-preserve-hoist.ll
create mode 100644 llvm/test/Transforms/SimplifyCFG/merge-direct-call-branch-weights-preserve-sink.ll
diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index edec0e7a94422..c136825d47b9c 100644
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -3355,9 +3355,10 @@ static void combineMetadata(Instruction *K, const Instruction *J,
case LLVMContext::MD_invariant_group:
// Preserve !invariant.group in K.
break;
- // Keep empty cases for mmra, memprof, and callsite to prevent them from
- // being removed as unknown metadata. The actual merging is handled
+ // Keep empty cases for prof, mmra, memprof, and callsite to prevent them
+ // from being removed as unknown metadata. The actual merging is handled
// separately below.
+ case LLVMContext::MD_prof:
case LLVMContext::MD_mmra:
case LLVMContext::MD_memprof:
case LLVMContext::MD_callsite:
@@ -3386,10 +3387,6 @@ static void combineMetadata(Instruction *K, const Instruction *J,
if (!AAOnly)
K->setMetadata(Kind, JMD);
break;
- case LLVMContext::MD_prof:
- if (!AAOnly && DoesKMove)
- K->setMetadata(Kind, MDNode::getMergedProfMetadata(KMD, JMD, K, J));
- break;
case LLVMContext::MD_noalias_addrspace:
if (DoesKMove)
K->setMetadata(Kind,
@@ -3436,6 +3433,16 @@ static void combineMetadata(Instruction *K, const Instruction *J,
K->setMetadata(LLVMContext::MD_callsite,
MDNode::getMergedCallsiteMetadata(KCallSite, JCallSite));
}
+
+ // Merge prof metadata.
+ // Handle separately to support cases where only one instruction has the
+ // metadata.
+ auto *JProf = J->getMetadata(LLVMContext::MD_prof);
+ auto *KProf = K->getMetadata(LLVMContext::MD_prof);
+ if (!AAOnly && (JProf || KProf)) {
+ K->setMetadata(LLVMContext::MD_prof,
+ MDNode::getMergedProfMetadata(KProf, JProf, K, J));
+ }
}
void llvm::combineMetadataForCSE(Instruction *K, const Instruction *J,
diff --git a/llvm/test/Transforms/SimplifyCFG/merge-direct-call-branch-weights-preserve-hoist.ll b/llvm/test/Transforms/SimplifyCFG/merge-direct-call-branch-weights-preserve-hoist.ll
new file mode 100644
index 0000000000000..d6058134f5285
--- /dev/null
+++ b/llvm/test/Transforms/SimplifyCFG/merge-direct-call-branch-weights-preserve-hoist.ll
@@ -0,0 +1,62 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --check-globals --version 2
+; RUN: opt < %s -passes='simplifycfg<no-sink-common-insts;hoist-common-insts>' -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s --check-prefix=HOIST
+
+; Test case based on C++ code with manualy annotated !prof metadata.
+; This is to test that when calls to 'func1' from 'if.then' block
+; and 'if.else' block are hoisted, the branch_weights are merged and
+; attached to merged call rather than dropped.
+;
+; int func1(int a, int b) ;
+; int func2(int a, int b) ;
+
+; int func(int a, int b, bool c) {
+; int sum= 0;
+; if(c) {
+; sum += func1(a, b);
+; } else {
+; sum += func1(a, b);
+; sum -= func2(a, b);
+; }
+; return sum;
+; }
+define i32 @_Z4funciib(i32 %a, i32 %b, i1 %c) {
+; HOIST-LABEL: define i32 @_Z4funciib
+; HOIST-SAME: (i32 [[A:%.*]], i32 [[B:%.*]], i1 [[C:%.*]]) {
+; HOIST-NEXT: entry:
+; HOIST-NEXT: [[CALL:%.*]] = tail call i32 @_Z5func1ii(i32 [[A]], i32 [[B]]), !prof [[PROF0:![0-9]+]]
+; HOIST-NEXT: br i1 [[C]], label [[IF_END:%.*]], label [[IF_ELSE:%.*]]
+; HOIST: if.else:
+; HOIST-NEXT: [[CALL3:%.*]] = tail call i32 @_Z5func2ii(i32 [[A]], i32 [[B]])
+; HOIST-NEXT: [[SUB:%.*]] = sub i32 [[CALL]], [[CALL3]]
+; HOIST-NEXT: br label [[IF_END]]
+; HOIST: if.end:
+; HOIST-NEXT: [[SUM_0:%.*]] = phi i32 [ [[SUB]], [[IF_ELSE]] ], [ [[CALL]], [[ENTRY:%.*]] ]
+; HOIST-NEXT: ret i32 [[SUM_0]]
+;
+entry:
+ br i1 %c, label %if.then, label %if.else
+
+if.then: ; preds = %entry
+ %call = tail call i32 @_Z5func1ii(i32 %a, i32 %b)
+ br label %if.end
+
+if.else: ; preds = %entry
+ %call1 = tail call i32 @_Z5func1ii(i32 %a, i32 %b), !prof !0
+ %call3 = tail call i32 @_Z5func2ii(i32 %a, i32 %b)
+ %sub = sub i32 %call1, %call3
+ br label %if.end
+
+if.end: ; preds = %if.else, %if.then
+ %sum.0 = phi i32 [ %call, %if.then ], [ %sub, %if.else ]
+ ret i32 %sum.0
+}
+
+declare i32 @_Z5func1ii(i32, i32)
+
+declare i32 @_Z5func2ii(i32, i32)
+
+!0 = !{!"branch_weights", i32 10}
+
+;.
+; HOIST: [[PROF0]] = !{!"branch_weights", i32 10}
+;.
diff --git a/llvm/test/Transforms/SimplifyCFG/merge-direct-call-branch-weights-preserve-sink.ll b/llvm/test/Transforms/SimplifyCFG/merge-direct-call-branch-weights-preserve-sink.ll
new file mode 100644
index 0000000000000..c4aed5eb95888
--- /dev/null
+++ b/llvm/test/Transforms/SimplifyCFG/merge-direct-call-branch-weights-preserve-sink.ll
@@ -0,0 +1,63 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --check-globals --version 2
+; RUN: opt < %s -passes='simplifycfg<sink-common-insts;no-hoist-common-insts>' -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s --check-prefix=SINK
+
+
+; Test case based on the following C++ code with manualy annotated !prof metadata.
+; This is to test that when calls to 'func1' from 'if.then' and 'if.else' are
+; sinked, the branch weights are merged and attached to sinked call.
+;
+; int func1(int a, int b) ;
+; int func2(int a, int b) ;
+
+; int func(int a, int b, bool c) {
+; int sum = 0;
+; if (c) {
+; sum += func1(a,b);
+; } else {
+; b -= func2(a,b);
+; sum += func1(a,b);
+; }
+; return sum;
+; }
+
+define i32 @_Z4funciib(i32 %a, i32 %b, i1 %c) {
+; SINK-LABEL: define i32 @_Z4funciib
+; SINK-SAME: (i32 [[A:%.*]], i32 [[B:%.*]], i1 [[C:%.*]]) {
+; SINK-NEXT: entry:
+; SINK-NEXT: br i1 [[C]], label [[IF_END:%.*]], label [[IF_ELSE:%.*]]
+; SINK: if.else:
+; SINK-NEXT: [[CALL1:%.*]] = tail call i32 @_Z5func2ii(i32 [[A]], i32 [[B]])
+; SINK-NEXT: [[SUB:%.*]] = sub i32 [[B]], [[CALL1]]
+; SINK-NEXT: br label [[IF_END]]
+; SINK: if.end:
+; SINK-NEXT: [[SUB_SINK:%.*]] = phi i32 [ [[SUB]], [[IF_ELSE]] ], [ [[B]], [[ENTRY:%.*]] ]
+; SINK-NEXT: [[CALL2:%.*]] = tail call i32 @_Z5func1ii(i32 [[A]], i32 [[SUB_SINK]]), !prof [[PROF0:![0-9]+]]
+; SINK-NEXT: ret i32 [[CALL2]]
+;
+entry:
+ br i1 %c, label %if.then, label %if.else
+
+if.then: ; preds = %entry
+ %call = tail call i32 @_Z5func1ii(i32 %a, i32 %b), !prof !0
+ br label %if.end
+
+if.else: ; preds = %entry
+ %call1 = tail call i32 @_Z5func2ii(i32 %a, i32 %b)
+ %sub = sub i32 %b, %call1
+ %call2 = tail call i32 @_Z5func1ii(i32 %a, i32 %sub)
+ br label %if.end
+
+if.end: ; preds = %if.else, %if.then
+ %sum.0 = phi i32 [ %call, %if.then ], [ %call2, %if.else ]
+ ret i32 %sum.0
+}
+
+declare i32 @_Z5func1ii(i32, i32)
+
+declare i32 @_Z5func2ii(i32, i32)
+
+!0 = !{!"branch_weights", i32 10}
+
+;.
+; SINK: [[PROF0]] = !{!"branch_weights", i32 10}
+;.
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