[PATCH] D110007: [IROutliner] Disallow functions that return twice

[Andrew Litteken via Phabricator via llvm-commits]

This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rG4be86d18c0fc: [IROutliner] Disallow outlining calls that return twice. (authored by AndrewLitteken).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D110007/new/

https://reviews.llvm.org/D110007

Files:
  llvm/include/llvm/Transforms/IPO/IROutliner.h
  llvm/test/Transforms/IROutliner/illegal-returns-twice.ll


Index: llvm/test/Transforms/IROutliner/illegal-returns-twice.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/IROutliner/illegal-returns-twice.ll
@@ -0,0 +1,66 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -S -verify -iroutliner -ir-outlining-no-cost < %s | FileCheck %s
+
+; This test checks that we do not outline functions that are marked as returns
+; twice, since these can alter the frame of the function and affect how the
+; outliner behaves, causing miscompiles.
+
+; Function Attrs: optsize returns_twice
+declare i32 @setjmp(i32*) local_unnamed_addr #1
+ at tmp_jmpb = global [37 x i32] zeroinitializer, align 16
+
+define void @function1() {
+; CHECK-LABEL: @function1(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[A:%.*]] = alloca i32, align 4
+; CHECK-NEXT:    [[B:%.*]] = alloca i32, align 4
+; CHECK-NEXT:    [[C:%.*]] = alloca i32, align 4
+; CHECK-NEXT:    store i32 2, i32* [[A]], align 4
+; CHECK-NEXT:    store i32 3, i32* [[B]], align 4
+; CHECK-NEXT:    store i32 4, i32* [[C]], align 4
+; CHECK-NEXT:    [[CALL:%.*]] = call i32 @setjmp(i32* getelementptr inbounds ([37 x i32], [37 x i32]* @tmp_jmpb, i64 0, i64 0))
+; CHECK-NEXT:    call void @outlined_ir_func_0(i32* [[A]], i32* [[B]], i32* [[C]])
+; CHECK-NEXT:    ret void
+;
+entry:
+  %a = alloca i32, align 4
+  %b = alloca i32, align 4
+  %c = alloca i32, align 4
+  store i32 2, i32* %a, align 4
+  store i32 3, i32* %b, align 4
+  store i32 4, i32* %c, align 4
+  %call = call i32 @setjmp(i32* getelementptr inbounds ([37 x i32], [37 x i32]* @tmp_jmpb, i64 0, i64 0))
+  %al = load i32, i32* %a
+  %bl = load i32, i32* %b
+  %cl = load i32, i32* %c
+  ret void
+}
+
+define void @function2() {
+; CHECK-LABEL: @function2(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[A:%.*]] = alloca i32, align 4
+; CHECK-NEXT:    [[B:%.*]] = alloca i32, align 4
+; CHECK-NEXT:    [[C:%.*]] = alloca i32, align 4
+; CHECK-NEXT:    store i32 2, i32* [[A]], align 4
+; CHECK-NEXT:    store i32 3, i32* [[B]], align 4
+; CHECK-NEXT:    store i32 4, i32* [[C]], align 4
+; CHECK-NEXT:    [[CALL:%.*]] = call i32 @setjmp(i32* getelementptr inbounds ([37 x i32], [37 x i32]* @tmp_jmpb, i64 0, i64 0))
+; CHECK-NEXT:    call void @outlined_ir_func_0(i32* [[A]], i32* [[B]], i32* [[C]])
+; CHECK-NEXT:    ret void
+;
+entry:
+  %a = alloca i32, align 4
+  %b = alloca i32, align 4
+  %c = alloca i32, align 4
+  store i32 2, i32* %a, align 4
+  store i32 3, i32* %b, align 4
+  store i32 4, i32* %c, align 4
+  %call = call i32 @setjmp(i32* getelementptr inbounds ([37 x i32], [37 x i32]* @tmp_jmpb, i64 0, i64 0))
+  %al = load i32, i32* %a
+  %bl = load i32, i32* %b
+  %cl = load i32, i32* %c
+  ret void
+}
+
+attributes #1 = { optsize returns_twice }
Index: llvm/include/llvm/Transforms/IPO/IROutliner.h
===================================================================
--- llvm/include/llvm/Transforms/IPO/IROutliner.h
+++ llvm/include/llvm/Transforms/IPO/IROutliner.h
@@ -367,6 +367,11 @@
       Function *F = CI.getCalledFunction();
       if (!F || CI.isIndirectCall() || !F->hasName())
         return false;
+      // Returning twice can cause issues with the state of the function call
+      // that were not expected when the function was used, so we do not include
+      // the call in outlined functions.
+      if (CI.canReturnTwice())
+        return false;
       return true;
     }
     // TODO: Handle FreezeInsts.  Since a frozen value could be frozen inside


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