From bee229d85dd6a7d4f707a6b51f9df841a3788a6c Mon Sep 17 00:00:00 2001
From: Chen Li <meloli87@gmail.com>
Date: Mon, 4 Jan 2016 23:28:57 +0000
Subject: [PATCH] [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

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@256792 91177308-0d34-0410-b5e6-96231b3b80d8
---
 .../InstCombine/InstructionCombining.cpp        |  5 ++---
 test/Transforms/InstCombine/token.ll            | 17 +++++++++++++++++
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/lib/Transforms/InstCombine/InstructionCombining.cpp b/lib/Transforms/InstCombine/InstructionCombining.cpp
index 7c46cfd28fc..903a0b5f540 100644
--- a/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -3021,7 +3021,7 @@ static bool prepareICWorklistFromFunction(Function &F, const DataLayout &DL,
       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 prepareICWorklistFromFunction(Function &F, const DataLayout &DL,
         ++NumDeadInst;
         MadeIRChange = true;
       }
-      if (!Inst->getType()->isTokenTy())
-        Inst->eraseFromParent();
+      Inst->eraseFromParent();
     }
   }
 
diff --git a/test/Transforms/InstCombine/token.ll b/test/Transforms/InstCombine/token.ll
index 0929cf7ebee..f96b85b4f22 100644
--- a/test/Transforms/InstCombine/token.ll
+++ b/test/Transforms/InstCombine/token.ll
@@ -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)
-- 
2.34.1