Enhance SRoA to promote allocas that are used by selects in some
common cases. This triggers a surprising number of times in SPEC2K6
because min/max idioms end up doing this. For example, code from the
STL ends up looking like this to SRoA:
%202 = load i64* %__old_size, align 8, !tbaa !3
%203 = load i64* %__old_size, align 8, !tbaa !3
%204 = load i64* %__n, align 8, !tbaa !3
%205 = icmp ult i64 %203, %204
%storemerge.i = select i1 %205, i64* %__n, i64* %__old_size
%206 = load i64* %storemerge.i, align 8, !tbaa !3
We can now promote both the __n and the __old_size allocas.
This addresses another chunk of rdar://7339113, poor codegen on
stringswitch.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124088 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/Transforms/ScalarRepl/phi-select.ll b/test/Transforms/ScalarRepl/phi-select.ll
index 06ee208..f612ed5 100644
--- a/test/Transforms/ScalarRepl/phi-select.ll
+++ b/test/Transforms/ScalarRepl/phi-select.ll
@@ -44,16 +44,15 @@
}
; CHECK: @test3
-; CHECK: %A.0 = alloca i32
-; CHECK: %A.1 = alloca i32
+; CHECK-NEXT: %Q = select i1 %c, i32 1, i32 2
+; CHECK-NEXT: ret i32 %Q
; rdar://8904039
define i32 @test3(i1 %c) {
-entry:
%A = alloca {i32, i32}
%B = getelementptr {i32, i32}* %A, i32 0, i32 0
store i32 1, i32* %B
%C = getelementptr {i32, i32}* %A, i32 0, i32 1
- store i32 2, i32* %B
+ store i32 2, i32* %C
%X = select i1 %c, i32* %B, i32* %C
%Q = load i32* %X
@@ -76,3 +75,58 @@
%Q = load i64* %Y
ret i64 %Q
}
+
+
+;;
+;; Tests for promoting allocas used by selects.
+;; rdar://7339113
+;;
+
+define i32 @test5(i32 *%P) nounwind readnone ssp {
+entry:
+ %b = alloca i32, align 8
+ store i32 2, i32* %b, align 8
+
+ ;; Select on constant condition should be folded.
+ %p.0 = select i1 false, i32* %b, i32* %P
+ store i32 123, i32* %p.0
+
+ %r = load i32* %b, align 8
+ ret i32 %r
+
+; CHECK: @test5
+; CHECK: store i32 123, i32* %P
+; CHECK: ret i32 2
+}
+
+define i32 @test6(i32 %x, i1 %c) nounwind readnone ssp {
+ %a = alloca i32, align 8
+ %b = alloca i32, align 8
+ store i32 1, i32* %a, align 8
+ store i32 2, i32* %b, align 8
+ %p.0 = select i1 %c, i32* %b, i32* %a
+ %r = load i32* %p.0, align 8
+ ret i32 %r
+; CHECK: @test6
+; CHECK-NEXT: %r = select i1 %c, i32 2, i32 1
+; CHECK-NEXT: ret i32 %r
+}
+
+; Verify that the loads happen where the loads are, not where the select is.
+define i32 @test7(i32 %x, i1 %c) nounwind readnone ssp {
+ %a = alloca i32, align 8
+ %b = alloca i32, align 8
+ store i32 1, i32* %a
+ store i32 2, i32* %b
+ %p.0 = select i1 %c, i32* %b, i32* %a
+
+ store i32 0, i32* %a
+
+ %r = load i32* %p.0, align 8
+ ret i32 %r
+; CHECK: @test7
+; CHECK-NOT: alloca i32
+; CHECK: %r = select i1 %c, i32 2, i32 0
+; CHECK: ret i32 %r
+}
+