From 05130597262f3ed00dc4881d64795d117c76e3fc Mon Sep 17 00:00:00 2001
From: Rafael Espindola <rafael.espindola@gmail.com>
Date: Thu, 16 Aug 2012 15:09:43 +0000
Subject: Teach GVN to reason about edges dominating uses. This allows it to
 handle cases where some fact lake a=b dominates a use in a phi, but doesn't
 dominate the basic block itself.

This feature could also be implemented by splitting critical edges, but at least
with the current algorithm reasoning about the dominance directly is faster.

The time for running "opt -O2" in the testcase in pr10584 is 1.003 times slower
and on gcc as a single file it is 1.0007 times faster.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@162023 91177308-0d34-0410-b5e6-96231b3b80d8
---
 test/Transforms/GVN/edge.ll | 60 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 60 insertions(+)
 create mode 100644 test/Transforms/GVN/edge.ll

(limited to 'test')

diff --git a/test/Transforms/GVN/edge.ll b/test/Transforms/GVN/edge.ll
new file mode 100644
index 0000000..32392f3
--- /dev/null
+++ b/test/Transforms/GVN/edge.ll
@@ -0,0 +1,60 @@
+; RUN: opt %s -gvn -S -o - | FileCheck %s
+
+define i32 @f1(i32 %x) {
+  ; CHECK: define i32 @f1(
+bb0:
+  %cmp = icmp eq i32 %x, 0
+  br i1 %cmp, label %bb2, label %bb1
+bb1:
+  br label %bb2
+bb2:
+  %cond = phi i32 [ %x, %bb0 ], [ 0, %bb1 ]
+  %foo = add i32 %cond, %x
+  ret i32 %foo
+  ; CHECK: bb2:
+  ; CHECK: ret i32 %x
+}
+
+define i32 @f2(i32 %x) {
+  ; CHECK: define i32 @f2(
+bb0:
+  %cmp = icmp ne i32 %x, 0
+  br i1 %cmp, label %bb1, label %bb2
+bb1:
+  br label %bb2
+bb2:
+  %cond = phi i32 [ %x, %bb0 ], [ 0, %bb1 ]
+  %foo = add i32 %cond, %x
+  ret i32 %foo
+  ; CHECK: bb2:
+  ; CHECK: ret i32 %x
+}
+
+define i32 @f3(i32 %x) {
+  ; CHECK: define i32 @f3(
+bb0:
+  switch i32 %x, label %bb1 [ i32 0, label %bb2]
+bb1:
+  br label %bb2
+bb2:
+  %cond = phi i32 [ %x, %bb0 ], [ 0, %bb1 ]
+  %foo = add i32 %cond, %x
+  ret i32 %foo
+  ; CHECK: bb2:
+  ; CHECK: ret i32 %x
+}
+
+declare void @g(i1)
+define void @f4(i8 * %x)  {
+; CHECK: define void @f4(
+bb0:
+  %y = icmp eq i8* null, %x
+  br i1 %y, label %bb2, label %bb1
+bb1:
+  br label %bb2
+bb2:
+  %zed = icmp eq i8* null, %x
+  call void @g(i1 %zed)
+; CHECK: call void @g(i1 %y)
+  ret void
+}
-- 
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