The inst combining of inttoptr into GEP with one index was using the bit size of

the type instead of the byte size. This was causing troublesome mis-compilations.

True to form, this took 2 days to find and is a one-line fix. :-P

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@48354 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index ec51508e657656f79d3b7e9bf3d377a230f312e9..9b423a40db1109cfb61cff385652376c925a3719 100644 (file)
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -7416,7 +7416,7 @@ Instruction *InstCombiner::visitIntToPtr(IntToPtrInst &CI) {
     // is a single-index GEP.
     if (X->getType() == CI.getType()) {
       // Get the size of the pointee type.
-      uint64_t Size = TD->getABITypeSizeInBits(DestPointee);
+      uint64_t Size = TD->getABITypeSize(DestPointee);
 
       // Convert the constant to intptr type.
       APInt Offset = Cst->getValue();

diff --git a/test/Transforms/InstCombine/2008-03-13-IntToPtr.ll b/test/Transforms/InstCombine/2008-03-13-IntToPtr.ll
new file mode 100644 (file)
index 0000000..31e7e35
--- /dev/null
+++ b/test/Transforms/InstCombine/2008-03-13-IntToPtr.ll
@@ -0,0 +1,9 @@
+; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep {16} | count 1
+
+define i8* @bork(i8** %qux) {
+  %tmp275 = load i8** %qux, align 1
+  %tmp275276 = ptrtoint i8* %tmp275 to i32
+  %tmp277 = add i32 %tmp275276, 16
+  %tmp277278 = inttoptr i32 %tmp277 to i8*
+  ret i8* %tmp277278
+}