[llvm] cc246d4 - [Transforms][CodeExtraction] bug fix regions with stackrestore (#118564)
via llvm-commits
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Thu Dec 19 08:19:15 PST 2024
Author: Abhay Kanhere
Date: 2024-12-19T09:19:11-07:00
New Revision: cc246d4a29a0ece8470d2baa1f98245446051fe3
URL: https://github.com/llvm/llvm-project/commit/cc246d4a29a0ece8470d2baa1f98245446051fe3
DIFF: https://github.com/llvm/llvm-project/commit/cc246d4a29a0ece8470d2baa1f98245446051fe3.diff
LOG: [Transforms][CodeExtraction] bug fix regions with stackrestore (#118564)
Ensure code extraction for outlining to a function does not create a function with stacksave of caller to restore stack (e.g. tail call).
Added:
llvm/test/Transforms/HotColdSplit/outline-inner-region-stacktoocomplex.ll
Modified:
llvm/lib/Transforms/Utils/CodeExtractor.cpp
Removed:
################################################################################
diff --git a/llvm/lib/Transforms/Utils/CodeExtractor.cpp b/llvm/lib/Transforms/Utils/CodeExtractor.cpp
index 610a77bc4c31ec..7ddb9e22c83441 100644
--- a/llvm/lib/Transforms/Utils/CodeExtractor.cpp
+++ b/llvm/lib/Transforms/Utils/CodeExtractor.cpp
@@ -627,6 +627,24 @@ bool CodeExtractor::isEligible() const {
return false;
}
}
+ // stacksave as input implies stackrestore in the outlined function.
+ // This can confuse prolog epilog insertion phase.
+ // stacksave's uses must not cross outlined function.
+ for (BasicBlock *BB : Blocks) {
+ for (Instruction &I : *BB) {
+ IntrinsicInst *II = dyn_cast<IntrinsicInst>(&I);
+ if (!II)
+ continue;
+ bool IsSave = II->getIntrinsicID() == Intrinsic::stacksave;
+ bool IsRestore = II->getIntrinsicID() == Intrinsic::stackrestore;
+ if (IsSave && any_of(II->users(), [&Blks = this->Blocks](User *U) {
+ return !definedInRegion(Blks, U);
+ }))
+ return false;
+ if (IsRestore && !definedInRegion(Blocks, II->getArgOperand(0)))
+ return false;
+ }
+ }
return true;
}
diff --git a/llvm/test/Transforms/HotColdSplit/outline-inner-region-stacktoocomplex.ll b/llvm/test/Transforms/HotColdSplit/outline-inner-region-stacktoocomplex.ll
new file mode 100644
index 00000000000000..2ef827b04e6e2a
--- /dev/null
+++ b/llvm/test/Transforms/HotColdSplit/outline-inner-region-stacktoocomplex.ll
@@ -0,0 +1,71 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt -S --passes=hotcoldsplit --hotcoldsplit-max-params=1 < %s | FileCheck %s
+
+target datalayout = "E-m:a-p:32:32-i64:64-n32"
+
+define void @foo(i32 %cond) {
+; CHECK-LABEL: define void @foo(
+; CHECK-SAME: i32 [[COND:%.*]]) {
+; CHECK-NEXT: [[ENTRY:.*:]]
+; CHECK-NEXT: [[COND_ADDR:%.*]] = alloca i32, align 4
+; CHECK-NEXT: store i32 [[COND]], ptr [[COND_ADDR]], align 4
+; CHECK-NEXT: [[TMP0:%.*]] = load i32, ptr [[COND_ADDR]], align 4
+; CHECK-NEXT: [[STKS:%.*]] = tail call ptr @llvm.stacksave.p0()
+; CHECK-NEXT: [[TOBOOL:%.*]] = icmp ne i32 [[TMP0]], 0
+; CHECK-NEXT: br i1 [[TOBOOL]], label %[[IF_THEN:.*]], label %[[IF_END2:.*]]
+; CHECK: [[IF_THEN]]:
+; CHECK-NEXT: [[TMP1:%.*]] = load i32, ptr [[COND_ADDR]], align 4
+; CHECK-NEXT: call void @sink(i32 [[TMP0]])
+; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i32 [[TMP1]], 10
+; CHECK-NEXT: br i1 [[CMP]], label %[[IF_THEN1:.*]], label %[[IF_ELSE:.*]]
+; CHECK: [[IF_THEN1]]:
+; CHECK-NEXT: call void @sideeffect(i32 2)
+; CHECK-NEXT: br label %[[IF_END:.*]]
+; CHECK: [[IF_ELSE]]:
+; CHECK-NEXT: call void @sink(i32 0)
+; CHECK-NEXT: call void @sideeffect(i32 0)
+; CHECK-NEXT: call void @llvm.stackrestore.p0(ptr [[STKS]])
+; CHECK-NEXT: br label %[[IF_END]]
+; CHECK: [[IF_END]]:
+; CHECK-NEXT: br label %[[IF_END2]]
+; CHECK: [[IF_END2]]:
+; CHECK-NEXT: call void @sideeffect(i32 1)
+; CHECK-NEXT: ret void
+;
+entry:
+ %cond.addr = alloca i32
+ store i32 %cond, ptr %cond.addr
+ %0 = load i32, ptr %cond.addr
+ %stks = tail call ptr @llvm.stacksave.p0()
+ %tobool = icmp ne i32 %0, 0
+ br i1 %tobool, label %if.then, label %if.end2
+
+if.then: ; preds = %entry
+ %1 = load i32, ptr %cond.addr
+ call void @sink(i32 %0)
+ %cmp = icmp sgt i32 %1, 10
+ br i1 %cmp, label %if.then1, label %if.else
+
+if.then1: ; preds = %if.then
+ call void @sideeffect(i32 2)
+ br label %if.end
+
+if.else: ; preds = %if.then
+ call void @sink(i32 0)
+ call void @sideeffect(i32 0)
+ call void @llvm.stackrestore.p0(ptr %stks)
+ br label %if.end
+
+
+if.end: ; preds = %if.else, %if.then1
+ br label %if.end2
+
+if.end2: ; preds = %entry
+ call void @sideeffect(i32 1)
+ ret void
+}
+
+
+declare void @sideeffect(i32)
+
+declare void @sink(i32) cold
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