enhance SRoA to promote allocas that are used by PHI nodes. This often

occurs because instcombine sinks loads and inserts phis.  This kicks in 
on such apps as 175.vpr, eon, 403.gcc, xalancbmk and a bunch of times in
spec2006 in some app that uses std::deque.

This resolves the last of rdar://7339113.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124090 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 24 insertions, 3 deletions

diff --git a/test/Transforms/ScalarRepl/phi-select.ll b/test/Transforms/ScalarRepl/phi-select.ll
index f612ed5..fa3972d 100644
--- a/test/Transforms/ScalarRepl/phi-select.ll
+++ b/test/Transforms/ScalarRepl/phi-select.ll
@@ -25,8 +25,8 @@ entry:
 }
 
 ; CHECK: @test2
-; CHECK: %A.0 = alloca i32
-; CHECK: %A.1 = alloca i32
+; CHECK: %X.ld = phi i32 [ 1, %entry ], [ 2, %T ]
+; CHECK-NEXT: ret i32 %X.ld
 define i32 @test2(i1 %c) {
 entry:
   %A = alloca {i32, i32}
@@ -35,7 +35,7 @@ entry:
   br i1 %c, label %T, label %F
 T:
   %C = getelementptr {i32, i32}* %A, i32 0, i32 1
-  store i32 2, i32* %B
+  store i32 2, i32* %C
   br label %F
 F:
   %X = phi i32* [%B, %entry], [%C, %T]
@@ -130,3 +130,24 @@ define i32 @test7(i32 %x, i1 %c) nounwind readnone ssp {
 ; CHECK: ret i32 %r
 }
 
+;; Promote allocs that are PHI'd together by moving the loads.
+define i32 @test8(i32 %x) nounwind readnone ssp {
+; CHECK: @test8
+; CHECK-NOT: load i32
+; CHECK-NOT: store i32
+; CHECK: %p.0.ld = phi i32 [ 2, %entry ], [ 1, %T ]
+; CHECK-NEXT: ret i32 %p.0.ld
+entry:
+  %a = alloca i32, align 8
+  %b = alloca i32, align 8
+  store i32 1, i32* %a, align 8
+  store i32 2, i32* %b, align 8
+  %c = icmp eq i32 %x, 0 
+  br i1 %c, label %T, label %Cont
+T:
+  br label %Cont
+Cont:
+  %p.0 = phi i32* [%b, %entry],[%a, %T]
+  %r = load i32* %p.0, align 8
+  ret i32 %r
+}