[llvm-commits] [llvm] r165476 - in /llvm/trunk: lib/Transforms/Scalar/SROA.cpp test/Transforms/SROA/basictest.ll

[Chandler Carruth]

Author: chandlerc
Date: Mon Oct  8 20:58:35 2012
New Revision: 165476

URL: http://llvm.org/viewvc/llvm-project?rev=165476&view=rev
Log:
Fix PR14034, an infloop / heap corruption / crash bug in the new SROA.
Thanks to Benjamin for the raw test case. This one took about 50 times
longer to reduce than to fix. =/

Modified:
    llvm/trunk/lib/Transforms/Scalar/SROA.cpp
    llvm/trunk/test/Transforms/SROA/basictest.ll

Modified: llvm/trunk/lib/Transforms/Scalar/SROA.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/SROA.cpp?rev=165476&r1=165475&r2=165476&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/SROA.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/SROA.cpp Mon Oct  8 20:58:35 2012
@@ -1786,6 +1786,8 @@
       ElementTy = SeqTy->getElementType();
       Indices.push_back(IRB.getInt(APInt(TD.getPointerSizeInBits(), 0)));
     } else if (StructType *STy = dyn_cast<StructType>(ElementTy)) {
+      if (STy->element_begin() == STy->element_end())
+        break; // Nothing left to descend into.
       ElementTy = *STy->element_begin();
       Indices.push_back(IRB.getInt32(0));
     } else {

Modified: llvm/trunk/test/Transforms/SROA/basictest.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SROA/basictest.ll?rev=165476&r1=165475&r2=165476&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/SROA/basictest.ll (original)
+++ llvm/trunk/test/Transforms/SROA/basictest.ll Mon Oct  8 20:58:35 2012
@@ -948,3 +948,23 @@
   ret double %ret
 ; CHECK: ret double %x
 }
+
+%PR14034.struct = type { { {} }, i32, %PR14034.list }
+%PR14034.list = type { %PR14034.list*, %PR14034.list* }
+
+define void @PR14034() {
+; This test case tries to form GEPs into the empty leading struct members, and
+; subsequently crashed (under valgrind) before we fixed the PR. The important
+; thing is to handle empty structs gracefully.
+; CHECK: @PR14034
+
+entry:
+  %a = alloca %PR14034.struct
+  %list = getelementptr %PR14034.struct* %a, i32 0, i32 2
+  %prev = getelementptr %PR14034.list* %list, i32 0, i32 1
+  store %PR14034.list* undef, %PR14034.list** %prev
+  %cast0 = bitcast %PR14034.struct* undef to i8*
+  %cast1 = bitcast %PR14034.struct* %a to i8*
+  call void @llvm.memcpy.p0i8.p0i8.i32(i8* %cast0, i8* %cast1, i32 12, i32 0, i1 false)
+  ret void
+}