SROA: Only split loads on byte boundaries
r199771 accidently broke the logic that makes sure that SROA only splits
load on byte boundaries. If such a split happens, some bits get lost
when reassembling loads of wider types, causing data corruption.
Move the width check up to reject such splits early, avoiding the
corruption. Fixes PR19250.
Patch by: Björn Steinbrink <bsteinbr@gmail.com>
llvm-svn: 211082
diff --git a/llvm/test/Transforms/SROA/slice-width.ll b/llvm/test/Transforms/SROA/slice-width.ll
new file mode 100644
index 0000000..179780b
--- /dev/null
+++ b/llvm/test/Transforms/SROA/slice-width.ll
@@ -0,0 +1,25 @@
+; RUN: opt < %s -sroa -S | FileCheck %s
+target datalayout = "e-p:64:64:64-p1:16:16:16-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-n8:16:32:64"
+
+declare void @llvm.memcpy.p0i8.p0i8.i32(i8* nocapture, i8* nocapture, i32, i32, i1) nounwind
+
+define void @no_split_on_non_byte_width(i32) {
+; This tests that allocas are not split into slices that are not byte width multiple
+ %arg = alloca i32 , align 8
+ store i32 %0, i32* %arg
+ br label %load_i32
+
+load_i32:
+; CHECK-LABEL: load_i32:
+; CHECK-NOT: bitcast {{.*}} to i1
+; CHECK-NOT: zext i1
+ %r0 = load i32* %arg
+ br label %load_i1
+
+load_i1:
+; CHECK-LABEL: load_i1:
+; CHECK: bitcast {{.*}} to i1
+ %p1 = bitcast i32* %arg to i1*
+ %t1 = load i1* %p1
+ ret void
+}