From 10cc45336d5b5fdcb66596a41b8d19de2834ad2f Mon Sep 17 00:00:00 2001
From: Andrew Trick <atrick@apple.com>
Date: Tue, 14 Feb 2012 00:00:23 +0000
Subject: Add simplifyLoopLatch to LoopRotate pass.

This folds a simple loop tail into a loop latch. It covers the common (in fortran) case of postincrement loops. It's a "free" way to expose this type of loop to downstream loop optimizations that bail out on non-canonical loops (getLoopLatch is a heavily used check).

llvm-svn: 150439
---
 llvm/test/Transforms/LoopRotate/simplifylatch.ll | 39 ++++++++++++++++++++++++
 1 file changed, 39 insertions(+)
 create mode 100644 llvm/test/Transforms/LoopRotate/simplifylatch.ll

(limited to 'llvm/test/Transforms/LoopRotate/simplifylatch.ll')

diff --git a/llvm/test/Transforms/LoopRotate/simplifylatch.ll b/llvm/test/Transforms/LoopRotate/simplifylatch.ll
new file mode 100644
index 00000000000..f4227245f74
--- /dev/null
+++ b/llvm/test/Transforms/LoopRotate/simplifylatch.ll
@@ -0,0 +1,39 @@
+; RUN: opt -S < %s -loop-rotate -verify-dom-info -verify-loop-info | FileCheck %s
+; PR2624 unroll multiple exits
+
+@mode_table = global [4 x i32] zeroinitializer		; <[4 x i32]*> [#uses=1]
+
+; CHECK: @f
+; CHECK-NOT: bb4
+define i8 @f() {
+entry:
+	tail call i32 @fegetround( )		; <i32>:0 [#uses=1]
+	br label %bb
+
+bb:		; preds = %bb4, %entry
+	%mode.0 = phi i8 [ 0, %entry ], [ %indvar.next, %bb4 ]		; <i8> [#uses=4]
+	zext i8 %mode.0 to i32		; <i32>:1 [#uses=1]
+	getelementptr [4 x i32]* @mode_table, i32 0, i32 %1		; <i32*>:2 [#uses=1]
+	load i32* %2, align 4		; <i32>:3 [#uses=1]
+	icmp eq i32 %3, %0		; <i1>:4 [#uses=1]
+	br i1 %4, label %bb1, label %bb2
+
+bb1:		; preds = %bb
+	ret i8 %mode.0
+
+bb2:		; preds = %bb
+	icmp eq i8 %mode.0, 1		; <i1>:5 [#uses=1]
+	br i1 %5, label %bb5, label %bb4
+
+bb4:		; preds = %bb2
+	%indvar.next = add i8 %mode.0, 1		; <i8> [#uses=1]
+	br label %bb
+
+bb5:		; preds = %bb2
+	tail call void @raise_exception( ) noreturn
+	unreachable
+}
+
+declare i32 @fegetround()
+
+declare void @raise_exception() noreturn
-- 
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