release/20.x: [GlobalOpt] Do not promote malloc if there are atomic loads/stores (#137158) #137179
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@fhahn What do you think about merging this PR to the release branch? |
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@llvm/pr-subscribers-llvm-transforms Author: None (llvmbot) ChangesBackport 57530c2 Requested by: @nikic Full diff: https://github.com/llvm/llvm-project/pull/137179.diff 2 Files Affected:
diff --git a/llvm/lib/Transforms/IPO/GlobalOpt.cpp b/llvm/lib/Transforms/IPO/GlobalOpt.cpp
index 9586fc97a39f7..236a531317678 100644
--- a/llvm/lib/Transforms/IPO/GlobalOpt.cpp
+++ b/llvm/lib/Transforms/IPO/GlobalOpt.cpp
@@ -719,10 +719,14 @@ static bool allUsesOfLoadedValueWillTrapIfNull(const GlobalVariable *GV) {
const Value *P = Worklist.pop_back_val();
for (const auto *U : P->users()) {
if (auto *LI = dyn_cast<LoadInst>(U)) {
+ if (!LI->isSimple())
+ return false;
SmallPtrSet<const PHINode *, 8> PHIs;
if (!AllUsesOfValueWillTrapIfNull(LI, PHIs))
return false;
} else if (auto *SI = dyn_cast<StoreInst>(U)) {
+ if (!SI->isSimple())
+ return false;
// Ignore stores to the global.
if (SI->getPointerOperand() != P)
return false;
diff --git a/llvm/test/Transforms/GlobalOpt/malloc-promote-atomic.ll b/llvm/test/Transforms/GlobalOpt/malloc-promote-atomic.ll
new file mode 100644
index 0000000000000..0ecdf095efdd8
--- /dev/null
+++ b/llvm/test/Transforms/GlobalOpt/malloc-promote-atomic.ll
@@ -0,0 +1,28 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt -passes=globalopt -S < %s | FileCheck %s
+
+@g = internal global ptr null, align 8
+
+define void @init() {
+; CHECK-LABEL: define void @init() local_unnamed_addr {
+; CHECK-NEXT: [[ALLOC:%.*]] = call ptr @malloc(i64 48)
+; CHECK-NEXT: store atomic ptr [[ALLOC]], ptr @g seq_cst, align 8
+; CHECK-NEXT: ret void
+;
+ %alloc = call ptr @malloc(i64 48)
+ store atomic ptr %alloc, ptr @g seq_cst, align 8
+ ret void
+}
+
+define i1 @check() {
+; CHECK-LABEL: define i1 @check() local_unnamed_addr {
+; CHECK-NEXT: [[VAL:%.*]] = load atomic ptr, ptr @g seq_cst, align 8
+; CHECK-NEXT: [[CMP:%.*]] = icmp eq ptr [[VAL]], null
+; CHECK-NEXT: ret i1 [[CMP]]
+;
+ %val = load atomic ptr, ptr @g seq_cst, align 8
+ %cmp = icmp eq ptr %val, null
+ ret i1 %cmp
+}
+
+declare ptr @malloc(i64) allockind("alloc,uninitialized") allocsize(0)
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Collaborator
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ping @fhahn |
github-project-automation
bot
moved this from Needs Review
to Needs Merge
in LLVM Release Status
…lvm#137158) When converting a malloc stored to a global into a global, we will introduce an i1 flag to track whether the global has been initialized. In case of atomic loads/stores, this will result in verifier failures, because atomic ops on i1 are illegal. Even if we changed this to i8, I don't think it is a good idea to change atomic types in that way. Instead, bail out of the transform is we encounter any atomic loads/stores of the global. Fixes llvm#137152. (cherry picked from commit 57530c2)
github-project-automation
bot
moved this from Needs Merge
to Done
in LLVM Release Status
|
@nikic (or anyone else). If you would like to add a note about this fix in the release notes (completely optional). Please reply to this comment with a one or two sentence description of the fix. When you are done, please add the release:note label to this PR. |
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Backport 57530c2
Requested by: @nikic