[llvm] r205547 - Fix PR19270 - type mismatch caused by invalid optimization.

[Eli Bendersky]

Author: eliben
Date: Thu Apr  3 12:51:58 2014
New Revision: 205547

URL: http://llvm.org/viewvc/llvm-project?rev=205547&view=rev
Log:
Fix PR19270 - type mismatch caused by invalid optimization.

Patch by Jingyue Wu.


Modified:
    llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp
    llvm/trunk/test/Transforms/InstCombine/gep-addrspace.ll

Modified: llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp?rev=205547&r1=205546&r2=205547&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp Thu Apr  3 12:51:58 2014
@@ -1241,7 +1241,15 @@ Instruction *InstCombiner::visitGetEleme
           GetElementPtrInst *Res =
             GetElementPtrInst::Create(StrippedPtr, Idx, GEP.getName());
           Res->setIsInBounds(GEP.isInBounds());
-          return Res;
+          if (StrippedPtrTy->getAddressSpace() == GEP.getAddressSpace())
+            return Res;
+          // Insert Res, and create an addrspacecast.
+          // e.g.,
+          // GEP (addrspacecast i8 addrspace(1)* X to [0 x i8]*), i32 0, ...
+          // ->
+          // %0 = GEP i8 addrspace(1)* X, ...
+          // addrspacecast i8 addrspace(1)* %0 to i8*
+          return new AddrSpaceCastInst(Builder->Insert(Res), GEP.getType());
         }
 
         if (ArrayType *XATy =
@@ -1253,8 +1261,24 @@ Instruction *InstCombiner::visitGetEleme
             // to an array of the same type as the destination pointer
             // array.  Because the array type is never stepped over (there
             // is a leading zero) we can fold the cast into this GEP.
-            GEP.setOperand(0, StrippedPtr);
-            return &GEP;
+            if (StrippedPtrTy->getAddressSpace() == GEP.getAddressSpace()) {
+              GEP.setOperand(0, StrippedPtr);
+              return &GEP;
+            }
+            // Cannot replace the base pointer directly because StrippedPtr's
+            // address space is different. Instead, create a new GEP followed by
+            // an addrspacecast.
+            // e.g.,
+            // GEP (addrspacecast [10 x i8] addrspace(1)* X to [0 x i8]*),
+            //   i32 0, ...
+            // ->
+            // %0 = GEP [10 x i8] addrspace(1)* X, ...
+            // addrspacecast i8 addrspace(1)* %0 to i8*
+            SmallVector<Value*, 8> Idx(GEP.idx_begin(), GEP.idx_end());
+            Value *NewGEP = GEP.isInBounds() ?
+              Builder->CreateInBoundsGEP(StrippedPtr, Idx, GEP.getName()) :
+              Builder->CreateGEP(StrippedPtr, Idx, GEP.getName());
+            return new AddrSpaceCastInst(NewGEP, GEP.getType());
           }
         }
       }

Modified: llvm/trunk/test/Transforms/InstCombine/gep-addrspace.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/gep-addrspace.ll?rev=205547&r1=205546&r2=205547&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/gep-addrspace.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/gep-addrspace.ll Thu Apr  3 12:51:58 2014
@@ -1,4 +1,4 @@
-; RUN: opt < %s -instcombine -S
+; RUN: opt < %s -instcombine -S | FileCheck %s
 
 target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
 target triple = "x86_64-pc-win32"
@@ -17,3 +17,18 @@ ST:
   ret void
 }
 
+ at array = internal addrspace(3) global [256 x float] zeroinitializer, align 4
+ at scalar = internal addrspace(3) global float 0.000000e+00, align 4
+
+define void @keep_necessary_addrspacecast(i64 %i, float** %out0, float** %out1) {
+entry:
+; CHECK-LABEL: @keep_necessary_addrspacecast
+  %0 = getelementptr [256 x float]* addrspacecast ([256 x float] addrspace(3)* @array to [256 x float]*), i64 0, i64 %i
+; CHECK: addrspacecast float addrspace(3)* %{{[0-9]+}} to float*
+  %1 = getelementptr [0 x float]* addrspacecast (float addrspace(3)* @scalar to [0 x float]*), i64 0, i64 %i
+; CHECK: addrspacecast float addrspace(3)* %{{[0-9]+}} to float*
+  store float* %0, float** %out0, align 4
+  store float* %1, float** %out1, align 4
+  ret void
+}
+