[PATCH] D20319: [InstCombine] Fix assertion when bitcast is converted to gep

[Gerolf Hoflehner via llvm-commits]

Gerolf created this revision.
Gerolf added a reviewer: llvm-commits.

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 patch suppresses the conversion in this case.

http://reviews.llvm.org/D20319

Files:
  lib/Transforms/InstCombine/InstCombineCasts.cpp
  test/Transforms/InstCombine/opaque.ll

Index: test/Transforms/InstCombine/opaque.ll
===================================================================
--- /dev/null
+++ test/Transforms/InstCombine/opaque.ll
@@ -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
+}
Index: lib/Transforms/InstCombine/InstCombineCasts.cpp
===================================================================
--- lib/Transforms/InstCombine/InstCombineCasts.cpp
+++ lib/Transforms/InstCombine/InstCombineCasts.cpp
@@ -1915,6 +1915,11 @@
       if (Instruction *V = PromoteCastOfAllocation(CI, *AI))
         return V;
 
+    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.


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