Generalize SROA to allow the first index of a GEP to be non-zero. Add a

missing check that an array reference doesn't go past the end of the array,
and remove some redundant checks for in-bound array and vector references
that are no longer needed.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91897 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 53 insertions, 0 deletions

diff --git a/test/Transforms/ScalarRepl/nonzero-first-index.ll b/test/Transforms/ScalarRepl/nonzero-first-index.ll
new file mode 100644
index 0000000000..60f414b717
--- /dev/null
+++ b/test/Transforms/ScalarRepl/nonzero-first-index.ll
@@ -0,0 +1,53 @@
+; RUN: opt < %s -scalarrepl -S | FileCheck %s
+
+target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:32:32-n8:16:32"
+target triple = "i386-pc-linux-gnu"
+
+%nested = type { i32, [4 x i32] }
+
+; Check that a GEP with a non-zero first index does not prevent SROA as long
+; as the resulting offset corresponds to an element in the alloca.
+define i32 @test1() {
+; CHECK: @test1
+; CHECK-NOT: = i160
+; CHECK: ret i32 undef
+	%A = alloca %nested
+	%B = getelementptr %nested* %A, i32 0, i32 1, i32 0
+	%C = getelementptr i32* %B, i32 2
+	%D = load i32* %C
+	ret i32 %D
+}
+
+; But, if the offset is out of range, then it should not be transformed.
+define i32 @test2() {
+; CHECK: @test2
+; CHECK: i160
+	%A = alloca %nested
+	%B = getelementptr %nested* %A, i32 0, i32 1, i32 0
+	%C = getelementptr i32* %B, i32 4
+	%D = load i32* %C
+	ret i32 %D
+}
+
+; Try it with a bitcast and single GEP....
+define i32 @test3() {
+; CHECK: @test3
+; CHECK-NOT: = i160
+; CHECK: ret i32 undef
+	%A = alloca %nested
+	%B = bitcast %nested* %A to i32*
+	%C = getelementptr i32* %B, i32 2
+	%D = load i32* %C
+	ret i32 %D
+}
+
+; ...and again make sure that out-of-range accesses are not transformed.
+define i32 @test4() {
+; CHECK: @test4
+; CHECK: i160
+	%A = alloca %nested
+	%B = bitcast %nested* %A to i32*
+	%C = getelementptr i32* %B, i32 -1
+	%D = load i32* %C
+	ret i32 %D
+}