[llvm] r256792 - [InstructionCombining] prepareICWorklistFromFunction halts in infinite loop with instructions of token type

[Chen Li via llvm-commits]

Author: chenli
Date: Mon Jan  4 17:28:57 2016
New Revision: 256792

URL: http://llvm.org/viewvc/llvm-project?rev=256792&view=rev
Log:
[InstructionCombining] prepareICWorklistFromFunction halts in infinite loop with instructions of token type

Summary: This patch fixes a bug in prepareICWorklistFromFunction, where the loop becomes infinite with instructions of token type. The patch checks if the instruction is token type, and if so it updates EndInst with the current instruction.

Reviewers: reames, majnemer

Subscribers: llvm-commits, sanjoy

Differential Revision: http://reviews.llvm.org/D15859

Modified:
    llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp
    llvm/trunk/test/Transforms/InstCombine/token.ll

Modified: llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp?rev=256792&r1=256791&r2=256792&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp Mon Jan  4 17:28:57 2016
@@ -3021,7 +3021,7 @@ static bool prepareICWorklistFromFunctio
       Instruction *Inst = &*--EndInst->getIterator();
       if (!Inst->use_empty() && !Inst->getType()->isTokenTy())
         Inst->replaceAllUsesWith(UndefValue::get(Inst->getType()));
-      if (Inst->isEHPad()) {
+      if (Inst->isEHPad() || Inst->getType()->isTokenTy()) {
         EndInst = Inst;
         continue;
       }
@@ -3029,8 +3029,7 @@ static bool prepareICWorklistFromFunctio
         ++NumDeadInst;
         MadeIRChange = true;
       }
-      if (!Inst->getType()->isTokenTy())
-        Inst->eraseFromParent();
+      Inst->eraseFromParent();
     }
   }
 

Modified: llvm/trunk/test/Transforms/InstCombine/token.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/token.ll?rev=256792&r1=256791&r2=256792&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/token.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/token.ll Mon Jan  4 17:28:57 2016
@@ -85,5 +85,22 @@ unreachable:
 ; CHECK:  %Y = zext i8 %B to i32
 ; CHECK:  %phi = phi i32 [ %X, %bb ], [ %Y, %cont ], [ %Y, %cont2 ]
 
+declare void @foo()
+declare token @llvm.experimental.gc.statepoint.p0f_isVoidf(i64, i32, void ()*, i32, i32, ...)
+
+define void @test4(i8 addrspace(1)* %obj) gc "statepoint-example" {
+bb:
+  unreachable
+
+unreachable:
+  call token (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 0, i32 0, void ()* @foo, i32 0, i32 0, i32 0, i32 5, i32 0, i32 -1, i32 0, i32 0, i32 0)
+  ret void
+}
+
+; CHECK-LABEL: define void @test4(
+; CHECK: unreachable:
+; CHECK:   call token (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 0, i32 0, void ()* @foo, i32 0, i32 0, i32 0, i32 5, i32 0, i32 -1, i32 0, i32 0, i32 0)
+; CHECK:   ret void
+
 
 declare void @g(i32)