[PATCH] R600: Fix an infinite loop when trying to reorganize export/tex vector input

[Vincent Lejeune]

http://llvm-reviews.chandlerc.com/D2368

Files:
  lib/Target/R600/R600ISelLowering.cpp
  test/CodeGen/R600/r600-infinite-loop-bug-while-reorganizing-vector.ll

Index: lib/Target/R600/R600ISelLowering.cpp
===================================================================
--- lib/Target/R600/R600ISelLowering.cpp
+++ lib/Target/R600/R600ISelLowering.cpp
@@ -1442,17 +1442,20 @@
       VectorEntry.getOperand(3)
   };
   bool isUnmovable[4] = { false, false, false, false };
-  for (unsigned i = 0; i < 4; i++)
+  for (unsigned i = 0; i < 4; i++) {
     RemapSwizzle[i] = i;
+    if (NewBldVec[i].getOpcode() == ISD::EXTRACT_VECTOR_ELT) {
+      unsigned Idx = dyn_cast<ConstantSDNode>(NewBldVec[i].getOperand(1))
+          ->getZExtValue();
+      if (i == Idx)
+        isUnmovable[Idx] = true;
+    }
+  }
 
   for (unsigned i = 0; i < 4; i++) {
     if (NewBldVec[i].getOpcode() == ISD::EXTRACT_VECTOR_ELT) {
       unsigned Idx = dyn_cast<ConstantSDNode>(NewBldVec[i].getOperand(1))
           ->getZExtValue();
-      if (i == Idx) {
-        isUnmovable[Idx] = true;
-        continue;
-      }
       if (isUnmovable[Idx])
         continue;
       // Swap i and Idx
Index: test/CodeGen/R600/r600-infinite-loop-bug-while-reorganizing-vector.ll
===================================================================
--- /dev/null
+++ test/CodeGen/R600/r600-infinite-loop-bug-while-reorganizing-vector.ll
@@ -0,0 +1,59 @@
+;RUN: llc < %s -march=r600 -mcpu=cayman
+;REQUIRES: asserts
+
+define void @main(<4 x float> inreg, <4 x float> inreg) #0 {
+main_body:
+  %2 = extractelement <4 x float> %0, i32 0
+  %3 = extractelement <4 x float> %0, i32 1
+  %4 = extractelement <4 x float> %0, i32 2
+  %5 = extractelement <4 x float> %0, i32 3
+  %6 = insertelement <4 x float> undef, float %2, i32 0
+  %7 = insertelement <4 x float> %6, float %3, i32 1
+  %8 = insertelement <4 x float> %7, float %4, i32 2
+  %9 = insertelement <4 x float> %8, float %5, i32 3
+  %10 = call <4 x float> @llvm.AMDGPU.cube(<4 x float> %9)
+  %11 = extractelement <4 x float> %10, i32 0
+  %12 = extractelement <4 x float> %10, i32 1
+  %13 = extractelement <4 x float> %10, i32 2
+  %14 = extractelement <4 x float> %10, i32 3
+  %15 = call float @fabs(float %13)
+  %16 = fdiv float 1.000000e+00, %15
+  %17 = fmul float %11, %16
+  %18 = fadd float %17, 1.500000e+00
+  %19 = fmul float %12, %16
+  %20 = fadd float %19, 1.500000e+00
+  %21 = insertelement <4 x float> undef, float %20, i32 0
+  %22 = insertelement <4 x float> %21, float %18, i32 1
+  %23 = insertelement <4 x float> %22, float %14, i32 2
+  %24 = insertelement <4 x float> %23, float %5, i32 3
+  %25 = extractelement <4 x float> %24, i32 0
+  %26 = extractelement <4 x float> %24, i32 1
+  %27 = extractelement <4 x float> %24, i32 2
+  %28 = extractelement <4 x float> %24, i32 3
+  %29 = insertelement <4 x float> undef, float %25, i32 0
+  %30 = insertelement <4 x float> %29, float %26, i32 1
+  %31 = insertelement <4 x float> %30, float %27, i32 2
+  %32 = insertelement <4 x float> %31, float %28, i32 3
+  %33 = call <4 x float> @llvm.AMDGPU.tex(<4 x float> %32, i32 16, i32 0, i32 13)
+  %34 = extractelement <4 x float> %33, i32 0
+  %35 = insertelement <4 x float> undef, float %34, i32 0
+  %36 = insertelement <4 x float> %35, float %34, i32 1
+  %37 = insertelement <4 x float> %36, float %34, i32 2
+  %38 = insertelement <4 x float> %37, float 1.000000e+00, i32 3
+  call void @llvm.R600.store.swizzle(<4 x float> %38, i32 0, i32 0)
+  ret void
+}
+
+; Function Attrs: readnone
+declare <4 x float> @llvm.AMDGPU.cube(<4 x float>) #1
+
+; Function Attrs: readnone
+declare float @fabs(float) #1
+
+; Function Attrs: readnone
+declare <4 x float> @llvm.AMDGPU.tex(<4 x float>, i32, i32, i32) #1
+
+declare void @llvm.R600.store.swizzle(<4 x float>, i32, i32)
+
+attributes #0 = { "ShaderType"="0" }
+attributes #1 = { readnone }
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