[llvm] r270479 - [InstCombine] Fix assertion when bitcast is converted to gep

[Gerolf Hoflehner via llvm-commits]

Author: ghoflehner
Date: Mon May 23 14:23:17 2016
New Revision: 270479

URL: http://llvm.org/viewvc/llvm-project?rev=270479&view=rev
Log:
[InstCombine] Fix assertion when bitcast is converted to gep

When an aggregate contains an opaque type its size cannot be
determined. This triggers an "Invalid GetElementPtrInst indices for type" assert
in function checkGEPType. The fix suppresses the conversion in this case.

http://reviews.llvm.org/D20319

Added:
    llvm/trunk/test/Transforms/InstCombine/opaque.ll
Modified:
    llvm/trunk/lib/Transforms/InstCombine/InstCombineCasts.cpp

Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineCasts.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineCasts.cpp?rev=270479&r1=270478&r2=270479&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineCasts.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineCasts.cpp Mon May 23 14:23:17 2016
@@ -1922,6 +1922,13 @@ Instruction *InstCombiner::visitBitCast(
       if (Instruction *V = PromoteCastOfAllocation(CI, *AI))
         return V;
 
+    // When the type pointed to is not sized the cast cannot be
+    // turned into a gep.
+    Type *PointeeType =
+        cast<PointerType>(Src->getType()->getScalarType())->getElementType();
+    if (!PointeeType->isSized())
+      return nullptr;
+
     // If the source and destination are pointers, and this cast is equivalent
     // to a getelementptr X, 0, 0, 0...  turn it into the appropriate gep.
     // This can enhance SROA and other transforms that want type-safe pointers.

Added: llvm/trunk/test/Transforms/InstCombine/opaque.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/opaque.ll?rev=270479&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/opaque.ll (added)
+++ llvm/trunk/test/Transforms/InstCombine/opaque.ll Mon May 23 14:23:17 2016
@@ -0,0 +1,32 @@
+; RUN: opt < %s -instcombine -disable-output
+; Checks that bitcasts are not converted into GEP when
+; when the size of an aggregate cannot be determined.
+%swift.opaque = type opaque
+%SQ = type <{ [8 x i8] }>
+%Si = type <{ i64 }>
+
+%V = type <{ <{ %Vs4Int8, %Vs4Int8, %Vs4Int8, %Vs4Int8, %Vs4Int8, %Vs4Int8, %Vs4Int8, %Vs4Int8 }>, %Si, %SQ, %SQ, %Si, %swift.opaque }>
+%Vs4Int8 = type <{ i8 }>
+%swift.type = type { i64 }
+
+declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture, i8* nocapture readonly,
+i64, i32, i1) #8
+
+ at _swift_slowAlloc = external global i8* (i64, i64)*
+
+declare i8* @rt_swift_slowAlloc(i64, i64)
+
+define  %swift.opaque* @_TwTkV([24 x i8]* %dest, %swift.opaque* %src,
+%swift.type* %bios_boot_params) #0 {
+entry:
+  %0 = bitcast %swift.opaque* %src to %V*
+  %1 = call noalias i8* @rt_swift_slowAlloc(i64 40, i64 0) #11
+  %2 = bitcast [24 x i8]* %dest to i8**
+  store i8* %1, i8** %2, align 8
+  %3 = bitcast i8* %1 to %V*
+  %4 = bitcast %V* %3 to i8*
+  %5 = bitcast %V* %0 to i8*
+  call void @llvm.memcpy.p0i8.p0i8.i64(i8* %4, i8* %5, i64 40, i32 1, i1 false)
+  %6 = bitcast %V* %3 to %swift.opaque*
+  ret %swift.opaque* %6
+}