<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><br class=""><div><blockquote type="cite" class=""><div class="">On Oct 7, 2015, at 2:06 AM, James Molloy <<a href="mailto:james@jamesmolloy.co.uk" class="">james@jamesmolloy.co.uk</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" class="">Hi Mehdi,<div class=""><br class=""></div><div class="">I've reverted this in r249528 as it was causing failures in all our internal builders and here too: <span style="line-height:1.5" class=""><a href="http://lab.llvm.org:8011/builders/clang-native-arm-lnt/builds/14453" class="">http://lab.llvm.org:8011/builders/clang-native-arm-lnt/builds/14453</a></span></div><div class=""><span style="line-height:1.5" class=""><br class=""></span></div><div class=""><span style="line-height:1.5" class="">Apologies,</span></div></div></div></blockquote><div><br class=""></div><div>No need to apologize, thanks for reverting, I’ll try to repro and figure out what went wrong.</div><div><br class=""></div><div>— </div><div>Mehdi</div><div><br class=""></div><div><br class=""></div><br class=""><blockquote type="cite" class=""><div class=""><div dir="ltr" class=""><div class=""><span style="line-height:1.5" class=""><br class=""></span></div><div class=""><span style="line-height:1.5" class="">James</span></div>
</div><br class=""><div class="gmail_quote"><div dir="ltr" class="">On Tue, 6 Oct 2015 at 18:21 Mehdi Amini via llvm-commits <<a href="mailto:llvm-commits@lists.llvm.org" class="">llvm-commits@lists.llvm.org</a>> wrote:<br class=""></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Author: mehdi_amini<br class="">
Date: Tue Oct 6 12:19:20 2015<br class="">
New Revision: 249431<br class="">
<br class="">
URL: <a href="http://llvm.org/viewvc/llvm-project?rev=249431&view=rev" rel="noreferrer" target="_blank" class="">http://llvm.org/viewvc/llvm-project?rev=249431&view=rev</a><br class="">
Log:<br class="">
This patch builds on top of D13378 to handle constant condition.<br class="">
<br class="">
With this patch, clang -O3 optimizes correctly providing > 1000x speedup on this artificial benchmark):<br class="">
<br class="">
for (a=0; a<n; a++)<br class="">
for (b=0; b<n; b++)<br class="">
for (c=0; c<n; c++)<br class="">
for (d=0; d<n; d++)<br class="">
for (e=0; e<n; e++)<br class="">
for (f=0; f<n; f++)<br class="">
x++;<br class="">
From test-suite/SingleSource/Benchmarks/Shootout/nestedloop.c<br class="">
<br class="">
Reviewers: sanjoyd<br class="">
<br class="">
Differential Revision: <a href="http://reviews.llvm.org/D13390" rel="noreferrer" target="_blank" class="">http://reviews.llvm.org/D13390</a><br class="">
<br class="">
From: Mehdi Amini <<a href="mailto:mehdi.amini@apple.com" target="_blank" class="">mehdi.amini@apple.com</a>><br class="">
<br class="">
Added:<br class="">
llvm/trunk/test/Analysis/ScalarEvolution/constant_condition.ll<br class="">
Modified:<br class="">
llvm/trunk/lib/Analysis/ScalarEvolution.cpp<br class="">
<br class="">
Modified: llvm/trunk/lib/Analysis/ScalarEvolution.cpp<br class="">
URL: <a href="http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ScalarEvolution.cpp?rev=249431&r1=249430&r2=249431&view=diff" rel="noreferrer" target="_blank" class="">http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ScalarEvolution.cpp?rev=249431&r1=249430&r2=249431&view=diff</a><br class="">
==============================================================================<br class="">
--- llvm/trunk/lib/Analysis/ScalarEvolution.cpp (original)<br class="">
+++ llvm/trunk/lib/Analysis/ScalarEvolution.cpp Tue Oct 6 12:19:20 2015<br class="">
@@ -3904,6 +3904,11 @@ const SCEV *ScalarEvolution::createNodeF<br class="">
Value *Cond,<br class="">
Value *TrueVal,<br class="">
Value *FalseVal) {<br class="">
+ // Handle "constant" branch or select. This can occur for instance when a<br class="">
+ // loop pass transforms an inner loop and moves on to process the outer loop.<br class="">
+ if (auto *CI = dyn_cast<ConstantInt>(Cond))<br class="">
+ return getSCEV(CI->isOne() ? TrueVal : FalseVal);<br class="">
+<br class="">
// Try to match some simple smax or umax patterns.<br class="">
auto *ICI = dyn_cast<ICmpInst>(Cond);<br class="">
if (!ICI)<br class="">
<br class="">
Added: llvm/trunk/test/Analysis/ScalarEvolution/constant_condition.ll<br class="">
URL: <a href="http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis/ScalarEvolution/constant_condition.ll?rev=249431&view=auto" rel="noreferrer" target="_blank" class="">http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis/ScalarEvolution/constant_condition.ll?rev=249431&view=auto</a><br class="">
==============================================================================<br class="">
--- llvm/trunk/test/Analysis/ScalarEvolution/constant_condition.ll (added)<br class="">
+++ llvm/trunk/test/Analysis/ScalarEvolution/constant_condition.ll Tue Oct 6 12:19:20 2015<br class="">
@@ -0,0 +1,51 @@<br class="">
+; RUN: opt -analyze -scalar-evolution < %s | FileCheck %s<br class="">
+<br class="">
+define i32 @branch_true(i32 %x, i32 %y) {<br class="">
+; CHECK-LABEL: Classifying expressions for: @branch_true<br class="">
+ entry:<br class="">
+ br i1 true, label %add, label %merge<br class="">
+<br class="">
+ add:<br class="">
+ %sum = add i32 %x, %y<br class="">
+ br label %merge<br class="">
+<br class="">
+ merge:<br class="">
+ %v = phi i32 [ %sum, %add ], [ %x, %entry ]<br class="">
+; CHECK: %v = phi i32 [ %sum, %add ], [ %x, %entry ]<br class="">
+; CHECK-NEXT: --> (%x + %y) U: full-set S: full-set<br class="">
+ ret i32 %v<br class="">
+}<br class="">
+<br class="">
+define i32 @branch_false(i32 %x, i32 %y) {<br class="">
+; CHECK-LABEL: Classifying expressions for: @branch_false<br class="">
+ entry:<br class="">
+ br i1 false, label %add, label %merge<br class="">
+<br class="">
+ add:<br class="">
+ %sum = add i32 %x, %y<br class="">
+ br label %merge<br class="">
+<br class="">
+ merge:<br class="">
+ %v = phi i32 [ %sum, %add ], [ %x, %entry ]<br class="">
+; CHECK: %v = phi i32 [ %sum, %add ], [ %x, %entry ]<br class="">
+; CHECK-NEXT: --> %x U: full-set S: full-set<br class="">
+ ret i32 %v<br class="">
+}<br class="">
+<br class="">
+define i32 @select_true(i32 %x, i32 %y) {<br class="">
+; CHECK-LABEL: Classifying expressions for: @select_true<br class="">
+ entry:<br class="">
+ %v = select i1 true, i32 %x, i32 %y<br class="">
+; CHECK: %v = select i1 true, i32 %x, i32 %y<br class="">
+; CHECK-NEXT: --> %x U: full-set S: full-set<br class="">
+ ret i32 %v<br class="">
+}<br class="">
+<br class="">
+define i32 @select_false(i32 %x, i32 %y) {<br class="">
+; CHECK-LABEL: Classifying expressions for: @select_false<br class="">
+ entry:<br class="">
+ %v = select i1 false, i32 %x, i32 %y<br class="">
+; CHECK: %v = select i1 false, i32 %x, i32 %y<br class="">
+; CHECK-NEXT: --> %y U: full-set S: full-set<br class="">
+ ret i32 %v<br class="">
+}<br class="">
<br class="">
<br class="">
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