Fix PR1749 and InstCombine/2007-10-28-EmptyField.ll by handling

zero-length fields better.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@43427 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 31 insertions, 1 deletions

diff --git a/lib/Target/TargetData.cpp b/lib/Target/TargetData.cpp
index b2d76d8418..b1b78a8ada 100644
--- a/lib/Target/TargetData.cpp
+++ b/lib/Target/TargetData.cpp
@@ -83,9 +83,15 @@ unsigned StructLayout::getElementContainingOffset(uint64_t Offset) const {
   assert(SI != &MemberOffsets[0] && "Offset not in structure type!");
   --SI;
   assert(*SI <= Offset && "upper_bound didn't work");
-  assert((SI == &MemberOffsets[0] || *(SI-1) < Offset) &&
+  assert((SI == &MemberOffsets[0] || *(SI-1) <= Offset) &&
          (SI+1 == &MemberOffsets[NumElements] || *(SI+1) > Offset) &&
          "Upper bound didn't work!");
+  
+  // Multiple fields can have the same offset if any of them are zero sized.
+  // For example, in { i32, [0 x i32], i32 }, searching for offset 4 will stop
+  // at the i32 element, because it is the last element at that offset.  This is
+  // the right one to return, because anything after it will have a higher
+  // offset, implying that this element is non-empty.
   return SI-&MemberOffsets[0];
 }
 
diff --git a/test/Transforms/InstCombine/2007-10-28-EmptyField.ll b/test/Transforms/InstCombine/2007-10-28-EmptyField.ll
new file mode 100644
index 0000000000..31ae985a6d
--- /dev/null
+++ b/test/Transforms/InstCombine/2007-10-28-EmptyField.ll
@@ -0,0 +1,24 @@
+; RUN: llvm-as < %s | opt -instcombine -disable-output
+; PR1749
+
+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"
+target triple = "x86_64-unknown-linux-gnu"
+	%struct.__large_struct = type { [100 x i64] }
+	%struct.compat_siginfo = type { i32, i32, i32, { [29 x i32] } }
+	%struct.siginfo_t = type { i32, i32, i32, { { i32, i32, [0 x i8], %struct.sigval_t, i32 }, [88 x i8] } }
+	%struct.sigval_t = type { i8* }
+
+define i32 @copy_siginfo_to_user32(%struct.compat_siginfo* %to, %struct.siginfo_t* %from) {
+entry:
+	%from_addr = alloca %struct.siginfo_t*		; <%struct.siginfo_t**> [#uses=1]
+	%tmp344 = load %struct.siginfo_t** %from_addr, align 8		; <%struct.siginfo_t*> [#uses=1]
+	%tmp345 = getelementptr %struct.siginfo_t* %tmp344, i32 0, i32 3		; <{ { i32, i32, [0 x i8], %struct.sigval_t, i32 }, [88 x i8] }*> [#uses=1]
+	%tmp346 = getelementptr { { i32, i32, [0 x i8], %struct.sigval_t, i32 }, [88 x i8] }* %tmp345, i32 0, i32 0		; <{ i32, i32, [0 x i8], %struct.sigval_t, i32 }*> [#uses=1]
+	%tmp346347 = bitcast { i32, i32, [0 x i8], %struct.sigval_t, i32 }* %tmp346 to { i32, i32, %struct.sigval_t }*		; <{ i32, i32, %struct.sigval_t }*> [#uses=1]
+	%tmp348 = getelementptr { i32, i32, %struct.sigval_t }* %tmp346347, i32 0, i32 2		; <%struct.sigval_t*> [#uses=1]
+	%tmp349 = getelementptr %struct.sigval_t* %tmp348, i32 0, i32 0		; <i8**> [#uses=1]
+	%tmp349350 = bitcast i8** %tmp349 to i32*		; <i32*> [#uses=1]
+	%tmp351 = load i32* %tmp349350, align 8		; <i32> [#uses=1]
+	%tmp360 = call i32 asm sideeffect "1:\09movl ${1:k},$2\0A2:\0A.section .fixup,\22ax\22\0A3:\09mov $3,$0\0A\09jmp 2b\0A.previous\0A.section __ex_table,\22a\22\0A\09.align 8\0A\09.quad 1b,3b\0A.previous", "=r,ir,*m,i,0,~{dirflag},~{fpsr},~{flags}"( i32 %tmp351, %struct.__large_struct* null, i32 -14, i32 0 )		; <i32> [#uses=0]
+	unreachable
+}