[llvm] r290191 - AMDGPU: Don't add same instruction multiple times to worklist

[Matt Arsenault via llvm-commits]

Author: arsenm
Date: Tue Dec 20 12:55:06 2016
New Revision: 290191

URL: http://llvm.org/viewvc/llvm-project?rev=290191&view=rev
Log:
AMDGPU: Don't add same instruction multiple times to worklist

When the instruction is processed the first time, it may be
deleted resulting in crashes. While the new test adds the same
user to the worklist twice, this particular case doesn't crash
but I'm not sure why.

Modified:
    llvm/trunk/lib/Target/AMDGPU/SIInstrInfo.cpp
    llvm/trunk/test/CodeGen/AMDGPU/sminmax.ll

Modified: llvm/trunk/lib/Target/AMDGPU/SIInstrInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/AMDGPU/SIInstrInfo.cpp?rev=290191&r1=290190&r2=290191&view=diff
==============================================================================
--- llvm/trunk/lib/Target/AMDGPU/SIInstrInfo.cpp (original)
+++ llvm/trunk/lib/Target/AMDGPU/SIInstrInfo.cpp Tue Dec 20 12:55:06 2016
@@ -3312,10 +3312,16 @@ void SIInstrInfo::addUsersToMoveToVALUWo
   MachineRegisterInfo &MRI,
   SmallVectorImpl<MachineInstr *> &Worklist) const {
   for (MachineRegisterInfo::use_iterator I = MRI.use_begin(DstReg),
-         E = MRI.use_end(); I != E; ++I) {
+         E = MRI.use_end(); I != E;) {
     MachineInstr &UseMI = *I->getParent();
     if (!canReadVGPR(UseMI, I.getOperandNo())) {
       Worklist.push_back(&UseMI);
+
+      do {
+        ++I;
+      } while (I != E && I->getParent() == &UseMI);
+    } else {
+      ++I;
     }
   }
 }

Modified: llvm/trunk/test/CodeGen/AMDGPU/sminmax.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/AMDGPU/sminmax.ll?rev=290191&r1=290190&r2=290191&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/AMDGPU/sminmax.ll (original)
+++ llvm/trunk/test/CodeGen/AMDGPU/sminmax.ll Tue Dec 20 12:55:06 2016
@@ -32,6 +32,20 @@ define void @v_abs_i32(i32 addrspace(1)*
   ret void
 }
 
+; GCN-LABEL: {{^}}v_abs_i32_repeat_user:
+; GCN: v_sub_i32_e32 [[NEG:v[0-9]+]], vcc, 0, [[SRC:v[0-9]+]]
+; GCN: v_max_i32_e32 [[MAX:v[0-9]+]], [[NEG]], [[SRC]]
+; GCN: v_mul_lo_i32 v{{[0-9]+}}, [[MAX]], [[MAX]]
+define void @v_abs_i32_repeat_user(i32 addrspace(1)* %out, i32 addrspace(1)* %src) nounwind {
+  %val = load i32, i32 addrspace(1)* %src, align 4
+  %neg = sub i32 0, %val
+  %cond = icmp sgt i32 %val, %neg
+  %res = select i1 %cond, i32 %val, i32 %neg
+  %mul = mul i32 %res, %res
+  store i32 %mul, i32 addrspace(1)* %out, align 4
+  ret void
+}
+
 ; FUNC-LABEL: {{^}}s_abs_v2i32:
 ; GCN: s_abs_i32
 ; GCN: s_abs_i32