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<p>I'll have to look at the compiler errors to see what's used. I
hadn't intended to leave any of the required functionality in
Transforms and I'm confused as to what I might have missed. I'm
hoping it's something minor.<br>
</p>
<br>
<div class="moz-cite-prefix">On 03/29/2018 10:24 AM, David Blaikie
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAENS6Eu-aY+L8T1_S84qx0C29Buqx6rqz=721OQmP2SPhXW_JA@mail.gmail.com">
<div dir="ltr">Ah, sorry - I think I tested that first & found
it was used. I forget what the particular use was - but should
be easy to reproduce & hopefully there's some good fix for
it. Happy to help with the implementation or ideas about how to
address it if you like.</div>
<br>
<div class="gmail_quote">
<div dir="ltr">On Thu, Mar 29, 2018 at 10:15 AM Philip Reames
<<a href="mailto:listmail@philipreames.com"
moz-do-not-send="true">listmail@philipreames.com</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF">
<p><br>
</p>
<br>
<div class="m_-6492984690386630205moz-cite-prefix">On
03/28/2018 04:16 PM, David Blaikie wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr"><br>
<br>
<div class="gmail_quote">
<div dir="ltr">On Tue, Mar 20, 2018 at 10:11 AM Philip
Reames via llvm-commits <<a
href="mailto:llvm-commits@lists.llvm.org"
target="_blank" moz-do-not-send="true">llvm-commits@lists.llvm.org</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">Author:
reames<br>
Date: Tue Mar 20 10:09:21 2018<br>
New Revision: 328004<br>
<br>
URL: <a
href="http://llvm.org/viewvc/llvm-project?rev=328004&view=rev"
rel="noreferrer" target="_blank"
moz-do-not-send="true">http://llvm.org/viewvc/llvm-project?rev=328004&view=rev</a><br>
Log:<br>
Add an analysis printer for must execute reasoning<br>
<br>
Many of our loop passes make use of so called "must
execute" or "guaranteed to execute" facts to prove
the legality of code motion. The basic notion is
that we know (by assumption) an instruction didn't
fault at it's original location, so if the location
we move it to is strictly post dominated by the
original, then we can't have introduced a new fault.<br>
<br>
At the moment, the testing for this logic is
somewhat adhoc and done mostly through LICM. Since
I'm working on that code, I want to improve the
testing. This patch is the first step in that
direction. It doesn't actually test the variant used
by the loop passes - I need to move that to the
Analysis library first - but instead exercises an
alternate implementation used by SCEV. (I plan on
merging both implementations.)<br>
<br>
Note: I'll be replacing the printing logic within
this with an annotation based version in the near
future. Anna suggested this in review, and it seems
like a strictly better format.<br>
<br>
Differential Revision: <a
href="https://reviews.llvm.org/D44524"
rel="noreferrer" target="_blank"
moz-do-not-send="true">https://reviews.llvm.org/D44524</a><br>
<br>
<br>
Added:<br>
llvm/trunk/lib/Analysis/MustExecute.cpp<br>
llvm/trunk/test/Analysis/MustExecute/<br>
llvm/trunk/test/Analysis/MustExecute/loop-header.ll<br>
Modified:<br>
llvm/trunk/include/llvm/Analysis/Passes.h<br>
llvm/trunk/include/llvm/InitializePasses.h<br>
llvm/trunk/include/llvm/LinkAllPasses.h<br>
llvm/trunk/lib/Analysis/Analysis.cpp<br>
llvm/trunk/lib/Analysis/CMakeLists.txt<br>
<br>
Modified: llvm/trunk/include/llvm/Analysis/Passes.h<br>
URL: <a
href="http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Analysis/Passes.h?rev=328004&r1=328003&r2=328004&view=diff"
rel="noreferrer" target="_blank"
moz-do-not-send="true">http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Analysis/Passes.h?rev=328004&r1=328003&r2=328004&view=diff</a><br>
==============================================================================<br>
--- llvm/trunk/include/llvm/Analysis/Passes.h
(original)<br>
+++ llvm/trunk/include/llvm/Analysis/Passes.h Tue
Mar 20 10:09:21 2018<br>
@@ -96,6 +96,14 @@ namespace llvm {<br>
//<br>
FunctionPass *createMemDerefPrinter();<br>
<br>
+
//===--------------------------------------------------------------------===//<br>
+ //<br>
+ // createMustExecutePrinter - This pass collects
information about which<br>
+ // instructions within a loop are guaranteed to
execute if the loop header is<br>
+ // entered and prints it with -analyze.<br>
+ //<br>
+ FunctionPass *createMustExecutePrinter();<br>
+<br>
}<br>
<br>
#endif<br>
<br>
Modified: llvm/trunk/include/llvm/InitializePasses.h<br>
URL: <a
href="http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/InitializePasses.h?rev=328004&r1=328003&r2=328004&view=diff"
rel="noreferrer" target="_blank"
moz-do-not-send="true">http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/InitializePasses.h?rev=328004&r1=328003&r2=328004&view=diff</a><br>
==============================================================================<br>
--- llvm/trunk/include/llvm/InitializePasses.h
(original)<br>
+++ llvm/trunk/include/llvm/InitializePasses.h Tue
Mar 20 10:09:21 2018<br>
@@ -268,6 +268,7 @@ void
initializeMergedLoadStoreMotionLega<br>
void initializeMetaRenamerPass(PassRegistry&);<br>
void
initializeModuleDebugInfoPrinterPass(PassRegistry&);<br>
void
initializeModuleSummaryIndexWrapperPassPass(PassRegistry&);<br>
+void
initializeMustExecutePrinterPass(PassRegistry&);<br>
void
initializeNameAnonGlobalLegacyPassPass(PassRegistry&);<br>
void
initializeNaryReassociateLegacyPassPass(PassRegistry&);<br>
void
initializeNewGVNLegacyPassPass(PassRegistry&);<br>
<br>
Modified: llvm/trunk/include/llvm/LinkAllPasses.h<br>
URL: <a
href="http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/LinkAllPasses.h?rev=328004&r1=328003&r2=328004&view=diff"
rel="noreferrer" target="_blank"
moz-do-not-send="true">http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/LinkAllPasses.h?rev=328004&r1=328003&r2=328004&view=diff</a><br>
==============================================================================<br>
--- llvm/trunk/include/llvm/LinkAllPasses.h
(original)<br>
+++ llvm/trunk/include/llvm/LinkAllPasses.h Tue Mar
20 10:09:21 2018<br>
@@ -207,6 +207,7 @@ namespace {<br>
(void) llvm::createRewriteSymbolsPass();<br>
(void)
llvm::createStraightLineStrengthReducePass();<br>
(void) llvm::createMemDerefPrinter();<br>
+ (void) llvm::createMustExecutePrinter();<br>
(void) llvm::createFloat2IntPass();<br>
(void)
llvm::createEliminateAvailableExternallyPass();<br>
(void)
llvm::createScalarizeMaskedMemIntrinPass();<br>
<br>
Modified: llvm/trunk/lib/Analysis/Analysis.cpp<br>
URL: <a
href="http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/Analysis.cpp?rev=328004&r1=328003&r2=328004&view=diff"
rel="noreferrer" target="_blank"
moz-do-not-send="true">http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/Analysis.cpp?rev=328004&r1=328003&r2=328004&view=diff</a><br>
==============================================================================<br>
--- llvm/trunk/lib/Analysis/Analysis.cpp (original)<br>
+++ llvm/trunk/lib/Analysis/Analysis.cpp Tue Mar 20
10:09:21 2018<br>
@@ -65,6 +65,7 @@ void
llvm::initializeAnalysis(PassRegist<br>
initializeMemoryDependenceWrapperPassPass(Registry);<br>
initializeModuleDebugInfoPrinterPass(Registry);<br>
initializeModuleSummaryIndexWrapperPassPass(Registry);<br>
+ initializeMustExecutePrinterPass(Registry);<br>
initializeObjCARCAAWrapperPassPass(Registry);<br>
initializeOptimizationRemarkEmitterWrapperPassPass(Registry);<br>
initializePostDominatorTreeWrapperPassPass(Registry);<br>
<br>
Modified: llvm/trunk/lib/Analysis/CMakeLists.txt<br>
URL: <a
href="http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/CMakeLists.txt?rev=328004&r1=328003&r2=328004&view=diff"
rel="noreferrer" target="_blank"
moz-do-not-send="true">http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/CMakeLists.txt?rev=328004&r1=328003&r2=328004&view=diff</a><br>
==============================================================================<br>
--- llvm/trunk/lib/Analysis/CMakeLists.txt
(original)<br>
+++ llvm/trunk/lib/Analysis/CMakeLists.txt Tue Mar
20 10:09:21 2018<br>
@@ -58,6 +58,7 @@ add_llvm_library(LLVMAnalysis<br>
MemorySSAUpdater.cpp<br>
ModuleDebugInfoPrinter.cpp<br>
ModuleSummaryAnalysis.cpp<br>
+ MustExecute.cpp<br>
ObjCARCAliasAnalysis.cpp<br>
ObjCARCAnalysisUtils.cpp<br>
ObjCARCInstKind.cpp<br>
<br>
Added: llvm/trunk/lib/Analysis/MustExecute.cpp<br>
URL: <a
href="http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/MustExecute.cpp?rev=328004&view=auto"
rel="noreferrer" target="_blank"
moz-do-not-send="true">http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/MustExecute.cpp?rev=328004&view=auto</a><br>
==============================================================================<br>
--- llvm/trunk/lib/Analysis/MustExecute.cpp (added)<br>
+++ llvm/trunk/lib/Analysis/MustExecute.cpp Tue Mar
20 10:09:21 2018<br>
@@ -0,0 +1,102 @@<br>
+//===- MustExecute.cpp - Printer for
isGuaranteedToExecute ----------------===//<br>
+//<br>
+// The LLVM Compiler
Infrastructure<br>
+//<br>
+// This file is distributed under the University of
Illinois Open Source<br>
+// License. See LICENSE.TXT for details.<br>
+//<br>
+//===----------------------------------------------------------------------===//<br>
+<br>
+#include "llvm/Analysis/LoopInfo.h"<br>
+#include "llvm/Analysis/Passes.h"<br>
+#include "llvm/Analysis/ValueTracking.h"<br>
+#include "llvm/IR/DataLayout.h"<br>
+#include "llvm/IR/InstIterator.h"<br>
+#include "llvm/IR/LLVMContext.h"<br>
+#include "llvm/IR/Module.h"<br>
+#include "llvm/Support/ErrorHandling.h"<br>
+#include "llvm/Support/raw_ostream.h"<br>
+#include "llvm/Transforms/Utils/LoopUtils.h"<br>
</blockquote>
<div><br>
This looks like a circular/invalid dependency?
Transforms depend on Analysis, not the other way
around?<br>
<br>
Would be great to get this fixed - happy to help, if
you've some ideas.<br>
<br>
Moving the whole LoopUtils isn't immediately
possible, its implementation depends on
BasicBlockUtils. (& also many of these utilities
seem more for mutation, which isn't relevant to
Analysis - so maybe it needs to be split up?)<br>
</div>
</div>
</div>
</blockquote>
</div>
<div text="#000000" bgcolor="#FFFFFF"> I think this is just a
stale header include. I'm building to confirm now and if so
will remove it. <br>
</div>
<div text="#000000" bgcolor="#FFFFFF">
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_quote">
<div> </div>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
+using namespace llvm;<br>
+<br>
+namespace {<br>
+ struct MustExecutePrinter : public FunctionPass {<br>
+ DenseMap<Value*, SmallVector<Loop*, 4>
> MustExec;<br>
+ SmallVector<Value *, 4> Ordering;<br>
+<br>
+ static char ID; // Pass identification,
replacement for typeid<br>
+ MustExecutePrinter() : FunctionPass(ID) {<br>
+
initializeMustExecutePrinterPass(*PassRegistry::getPassRegistry());<br>
+ }<br>
+ void getAnalysisUsage(AnalysisUsage &AU)
const override {<br>
+ AU.setPreservesAll();<br>
+
AU.addRequired<DominatorTreeWrapperPass>();<br>
+ AU.addRequired<LoopInfoWrapperPass>();<br>
+ }<br>
+ bool runOnFunction(Function &F) override;<br>
+ void print(raw_ostream &OS, const Module *
= nullptr) const override;<br>
+ void releaseMemory() override {<br>
+ MustExec.clear();<br>
+ Ordering.clear();<br>
+ }<br>
+ };<br>
+}<br>
+<br>
+char MustExecutePrinter::ID = 0;<br>
+INITIALIZE_PASS_BEGIN(MustExecutePrinter,
"print-mustexecute",<br>
+ "Instructions which execute
on loop entry", false, true)<br>
+INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)<br>
+INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)<br>
+INITIALIZE_PASS_END(MustExecutePrinter,
"print-mustexecute",<br>
+ "Instructions which execute on
loop entry", false, true)<br>
+<br>
+FunctionPass *llvm::createMustExecutePrinter() {<br>
+ return new MustExecutePrinter();<br>
+}<br>
+<br>
+bool isMustExecuteIn(Instruction &I, Loop *L,
DominatorTree *DT) {<br>
+ // TODO: move loop specific code to analysis<br>
+ //LoopSafetyInfo LSI;<br>
+ //computeLoopSafetyInfo(&LSI, L);<br>
+ //return isGuaranteedToExecute(I, DT, L,
&LSI);<br>
+ return
isGuaranteedToExecuteForEveryIteration(&I, L);<br>
+}<br>
+<br>
+bool MustExecutePrinter::runOnFunction(Function
&F) {<br>
+ auto &LI =
getAnalysis<LoopInfoWrapperPass>().getLoopInfo();<br>
+ auto &DT =
getAnalysis<DominatorTreeWrapperPass>().getDomTree();<br>
+ for (auto &I: instructions(F)) {<br>
+ Loop *L = LI.getLoopFor(I.getParent());<br>
+ while (L) {<br>
+ if (isMustExecuteIn(I, L, &DT)) {<br>
+ if (!MustExec.count(&I))<br>
+ Ordering.push_back(&I);<br>
+ MustExec[&I].push_back(L);<br>
+ }<br>
+ L = L->getParentLoop();<br>
+ };<br>
+ }<br>
+ return false;<br>
+}<br>
+<br>
+void MustExecutePrinter::print(raw_ostream &OS,
const Module *M) const {<br>
+ OS << "The following are guaranteed to
execute (for the respective loops):\n";<br>
+ for (Value *V: Ordering) {<br>
+ V->printAsOperand(OS);<br>
+ auto NumLoops = MustExec.lookup(V).size();<br>
+ if (NumLoops > 1)<br>
+ OS << "\t(mustexec in " <<
NumLoops << " loops: ";<br>
+ else<br>
+ OS << "\t(mustexec in: ";<br>
+<br>
+ bool first = true;<br>
+ for (const Loop *L : MustExec.lookup(V)) {<br>
+ if (!first)<br>
+ OS << ", ";<br>
+ first = false;<br>
+ OS << L->getHeader()->getName();<br>
+ }<br>
+ OS << ")\n";<br>
+ }<br>
+ OS << "\n";<br>
+}<br>
<br>
Added:
llvm/trunk/test/Analysis/MustExecute/loop-header.ll<br>
URL: <a
href="http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis/MustExecute/loop-header.ll?rev=328004&view=auto"
rel="noreferrer" target="_blank"
moz-do-not-send="true">http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis/MustExecute/loop-header.ll?rev=328004&view=auto</a><br>
==============================================================================<br>
---
llvm/trunk/test/Analysis/MustExecute/loop-header.ll
(added)<br>
+++
llvm/trunk/test/Analysis/MustExecute/loop-header.ll
Tue Mar 20 10:09:21 2018<br>
@@ -0,0 +1,80 @@<br>
+; RUN: opt -analyze -print-mustexecute %s<br>
+<br>
+; CHECK: Printing analysis 'Instructions which
execute on loop entry' for function
'header_with_icf':<br>
+; CHECK: The following are guaranteed to execute
(for the respective loops):<br>
+; CHECK: %iv = phi i32 [ 0, %entry ], [ %iv.next,
%loop ] (mustexec in: loop)<br>
+; CHECK: %v = load i32, i32* %p (mustexec
in: loop)<br>
+; CHECK: call void @maythrow_and_use(i32 %v)
(mustexec in: loop)<br>
+; CHECK-NOT: add<br>
+define i1 @header_with_icf(i32* noalias %p, i32
%high) {<br>
+entry:<br>
+ br label %loop<br>
+<br>
+loop:<br>
+ %iv = phi i32 [0, %entry], [%iv.next, %loop]<br>
+ %v = load i32, i32* %p<br>
+ call void @maythrow_and_use(i32 %v)<br>
+ %iv.next = add nsw nuw i32 %iv, 1<br>
+ %exit.test = icmp slt i32 %iv, %high<br>
+ br i1 %exit.test, label %exit, label %loop<br>
+<br>
+exit:<br>
+ ret i1 false<br>
+}<br>
+<br>
+; CHECK: Printing analysis 'Instructions which
execute on loop entry' for function 'test':<br>
+; CHECK: The following are guaranteed to execute
(for the respective loops):<br>
+; CHECK: %iv = phi i32 [ 0, %entry ], [ %iv.next,
%next ] (mustexec in: loop)<br>
+; CHECK: %v = load i32, i32* %p (mustexec
in: loop)<br>
+; CHECK: br label %next (mustexec in: loop)<br>
+define i1 @test(i32* noalias %p, i32 %high) {<br>
+entry:<br>
+ br label %loop<br>
+<br>
+loop:<br>
+ %iv = phi i32 [0, %entry], [%iv.next, %next]<br>
+ %v = load i32, i32* %p<br>
+ br label %next<br>
+next:<br>
+ call void @maythrow_and_use(i32 %v)<br>
+ %iv.next = add nsw nuw i32 %iv, 1<br>
+ %exit.test = icmp slt i32 %iv, %high<br>
+ br i1 %exit.test, label %exit, label %loop<br>
+<br>
+exit:<br>
+ ret i1 false<br>
+}<br>
+<br>
+; CHECK: Printing analysis 'Instructions which
execute on loop entry' for function 'nested':<br>
+; CHECK: The following are guaranteed to execute
(for the respective loops):<br>
+; CHECK: %iv = phi i32 [ 0, %entry ], [ %iv.next,
%next ] (mustexec in: loop)<br>
+; CHECK: br label %inner_loop (mustexec
in: loop)<br>
+; FIXME: These three are also must execute for the
outer loop.<br>
+; CHECK: %v = load i32, i32* %p (mustexec
in: inner_loop)<br>
+; CHECK: %inner.test = icmp eq i32 %v, 0
(mustexec in: inner_loop)<br>
+; CHECK: br i1 %inner.test, label %inner_loop,
label %next (mustexec in: inner_loop)<br>
+define i1 @nested(i32* noalias %p, i32 %high) {<br>
+entry:<br>
+ br label %loop<br>
+<br>
+loop:<br>
+ %iv = phi i32 [0, %entry], [%iv.next, %next]<br>
+ br label %inner_loop<br>
+<br>
+inner_loop:<br>
+ %v = load i32, i32* %p<br>
+ %inner.test = icmp eq i32 %v, 0<br>
+ br i1 %inner.test, label %inner_loop, label %next<br>
+<br>
+next:<br>
+ call void @maythrow_and_use(i32 %v)<br>
+ %iv.next = add nsw nuw i32 %iv, 1<br>
+ %exit.test = icmp slt i32 %iv, %high<br>
+ br i1 %exit.test, label %exit, label %loop<br>
+<br>
+exit:<br>
+ ret i1 false<br>
+}<br>
+<br>
+<br>
+declare void @maythrow_and_use(i32)<br>
<br>
<br>
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</blockquote>
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</blockquote>
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</blockquote>
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