Fix PR2488, a case where we deleted stack restores too aggressively.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@52702 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index 37637bbe63b86efb06eee8c0c3c890db14b3333e..d45eb99d939294db6a77adbf24045b5969155623 100644 (file)
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -8697,13 +8697,18 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) {
         CannotRemove = true;
         break;
       }
-      if (isa<CallInst>(BI)) {
-        if (!isa<IntrinsicInst>(BI)) {
+      if (CallInst *BCI = dyn_cast<CallInst>(BI)) {
+        if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(BCI)) {
+          // If there is a stackrestore below this one, remove this one.
+          if (II->getIntrinsicID() == Intrinsic::stackrestore)
+            return EraseInstFromFunction(CI);
+          // Otherwise, ignore the intrinsic.
+        } else {
+          // If we found a non-intrinsic call, we can't remove the stack
+          // restore.
           CannotRemove = true;
           break;
         }
-        // If there is a stackrestore below this one, remove this one.
-        return EraseInstFromFunction(CI);
       }
     }
     

diff --git a/test/Transforms/InstCombine/2008-06-24-StackRestore.ll b/test/Transforms/InstCombine/2008-06-24-StackRestore.ll
new file mode 100644 (file)
index 0000000..9ed7be3
--- /dev/null
+++ b/test/Transforms/InstCombine/2008-06-24-StackRestore.ll
@@ -0,0 +1,39 @@
+; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep {call.*llvm.stackrestore}
+; PR2488
+target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:32:32"
+target triple = "i386-pc-linux-gnu"
+@p = weak global i8* null              ; <i8**> [#uses=2]
+
+define i32 @main() nounwind  {
+entry:
+       %tmp248 = call i8* @llvm.stacksave( )           ; <i8*> [#uses=1]
+       %tmp2752 = alloca i32           ; <i32*> [#uses=2]
+       %tmpcast53 = bitcast i32* %tmp2752 to i8*               ; <i8*> [#uses=1]
+       store i32 2, i32* %tmp2752, align 4
+       volatile store i8* %tmpcast53, i8** @p, align 4
+       br label %bb44
+
+bb:            ; preds = %bb44
+       ret i32 0
+
+bb44:          ; preds = %bb44, %entry
+       %indvar = phi i32 [ 0, %entry ], [ %tmp3857, %bb44 ]            ; <i32> [#uses=1]
+       %tmp249 = phi i8* [ %tmp248, %entry ], [ %tmp2, %bb44 ]         ; <i8*> [#uses=1]
+       %tmp3857 = add i32 %indvar, 1           ; <i32> [#uses=3]
+       call void @llvm.stackrestore( i8* %tmp249 )
+       %tmp2 = call i8* @llvm.stacksave( )             ; <i8*> [#uses=1]
+       %tmp4 = srem i32 %tmp3857, 1000         ; <i32> [#uses=2]
+       %tmp5 = add i32 %tmp4, 1                ; <i32> [#uses=1]
+       %tmp27 = alloca i32, i32 %tmp5          ; <i32*> [#uses=3]
+       %tmpcast = bitcast i32* %tmp27 to i8*           ; <i8*> [#uses=1]
+       store i32 1, i32* %tmp27, align 4
+       %tmp34 = getelementptr i32* %tmp27, i32 %tmp4           ; <i32*> [#uses=1]
+       store i32 2, i32* %tmp34, align 4
+       volatile store i8* %tmpcast, i8** @p, align 4
+       %exitcond = icmp eq i32 %tmp3857, 999999                ; <i1> [#uses=1]
+       br i1 %exitcond, label %bb, label %bb44
+}
+
+declare i8* @llvm.stacksave() nounwind 
+
+declare void @llvm.stackrestore(i8*) nounwind