[llvm] r340319 - [GVN] Assign new value number to calls reading memory, if there is no MemDep info.
Florian Hahn via llvm-commits
llvm-commits at lists.llvm.org
Tue Aug 21 12:11:28 PDT 2018
Author: fhahn
Date: Tue Aug 21 12:11:27 2018
New Revision: 340319
URL: http://llvm.org/viewvc/llvm-project?rev=340319&view=rev
Log:
[GVN] Assign new value number to calls reading memory, if there is no MemDep info.
Currently we assign the same value number to two calls reading the same
memory location if we do not have MemoryDependence info. Without MemDep
Info we cannot guarantee that there is no store between the two calls, so we
have to assign a new number to the second call.
It also adds a new option EnableMemDep to enable/disable running
MemoryDependenceAnalysis and also renamed NoLoads to NoMemDepAnalysis to
be more explicit what it does. As it also impacts calls that read memory,
NoLoads is a bit confusing.
Reviewers: efriedma, sebpop, john.brawn, wmi
Reviewed By: efriedma
Differential Revision: https://reviews.llvm.org/D50893
Added:
llvm/trunk/test/Transforms/GVN/no-mem-dep-info.ll
Modified:
llvm/trunk/lib/Transforms/Scalar/GVN.cpp
Modified: llvm/trunk/lib/Transforms/Scalar/GVN.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/GVN.cpp?rev=340319&r1=340318&r2=340319&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/GVN.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/GVN.cpp Tue Aug 21 12:11:27 2018
@@ -98,6 +98,7 @@ STATISTIC(NumPRELoad, "Number of loads
static cl::opt<bool> EnablePRE("enable-pre",
cl::init(true), cl::Hidden);
static cl::opt<bool> EnableLoadPRE("enable-load-pre", cl::init(true));
+static cl::opt<bool> EnableMemDep("enable-gvn-memdep", cl::init(true));
// Maximum allowed recursion depth.
static cl::opt<uint32_t>
@@ -393,18 +394,13 @@ uint32_t GVN::ValueTable::lookupOrAddCal
uint32_t e = assignExpNewValueNum(exp).first;
valueNumbering[C] = e;
return e;
- } else if (AA->onlyReadsMemory(C)) {
+ } else if (MD && AA->onlyReadsMemory(C)) {
Expression exp = createExpr(C);
auto ValNum = assignExpNewValueNum(exp);
if (ValNum.second) {
valueNumbering[C] = ValNum.first;
return ValNum.first;
}
- if (!MD) {
- uint32_t e = assignExpNewValueNum(exp).first;
- valueNumbering[C] = e;
- return e;
- }
MemDepResult local_dep = MD->getDependency(C);
@@ -2520,8 +2516,8 @@ class llvm::gvn::GVNLegacyPass : public
public:
static char ID; // Pass identification, replacement for typeid
- explicit GVNLegacyPass(bool NoLoads = false)
- : FunctionPass(ID), NoLoads(NoLoads) {
+ explicit GVNLegacyPass(bool NoMemDepAnalysis = !EnableMemDep)
+ : FunctionPass(ID), NoMemDepAnalysis(NoMemDepAnalysis) {
initializeGVNLegacyPassPass(*PassRegistry::getPassRegistry());
}
@@ -2536,7 +2532,7 @@ public:
getAnalysis<DominatorTreeWrapperPass>().getDomTree(),
getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(),
getAnalysis<AAResultsWrapperPass>().getAAResults(),
- NoLoads ? nullptr
+ NoMemDepAnalysis ? nullptr
: &getAnalysis<MemoryDependenceWrapperPass>().getMemDep(),
LIWP ? &LIWP->getLoopInfo() : nullptr,
&getAnalysis<OptimizationRemarkEmitterWrapperPass>().getORE());
@@ -2546,7 +2542,7 @@ public:
AU.addRequired<AssumptionCacheTracker>();
AU.addRequired<DominatorTreeWrapperPass>();
AU.addRequired<TargetLibraryInfoWrapperPass>();
- if (!NoLoads)
+ if (!NoMemDepAnalysis)
AU.addRequired<MemoryDependenceWrapperPass>();
AU.addRequired<AAResultsWrapperPass>();
@@ -2557,7 +2553,7 @@ public:
}
private:
- bool NoLoads;
+ bool NoMemDepAnalysis;
GVN Impl;
};
@@ -2574,6 +2570,6 @@ INITIALIZE_PASS_DEPENDENCY(OptimizationR
INITIALIZE_PASS_END(GVNLegacyPass, "gvn", "Global Value Numbering", false, false)
// The public interface to this file...
-FunctionPass *llvm::createGVNPass(bool NoLoads) {
- return new GVNLegacyPass(NoLoads);
+FunctionPass *llvm::createGVNPass(bool NoMemDepAnalysis) {
+ return new GVNLegacyPass(NoMemDepAnalysis);
}
Added: llvm/trunk/test/Transforms/GVN/no-mem-dep-info.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/GVN/no-mem-dep-info.ll?rev=340319&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/GVN/no-mem-dep-info.ll (added)
+++ llvm/trunk/test/Transforms/GVN/no-mem-dep-info.ll Tue Aug 21 12:11:27 2018
@@ -0,0 +1,29 @@
+; RUN: opt %s -gvn -S -enable-gvn-memdep=false | FileCheck %s
+; RUN: opt %s -gvn -S -enable-gvn-memdep=true | FileCheck %s
+
+; Check that llvm.x86.avx2.gather.d.ps.256 intrinsic is not eliminated by GVN
+; with and without memory dependence info.
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; Function Attrs: nounwind readonly
+declare <8 x float> @llvm.x86.avx2.gather.d.ps.256(<8 x float>, i8*, <8 x i32>, <8 x float>, i8) #0
+
+; Function Attrs: nounwind
+define <8 x float> @foo1(i8* noalias readonly %arr.ptr, <8 x i32>* noalias readonly %vix.ptr, i8* noalias %t2.ptr) #1 {
+allocas:
+ %vix = load <8 x i32>, <8 x i32>* %vix.ptr, align 4
+ %t1.ptr = getelementptr i8, i8* %arr.ptr, i8 4
+
+ %v1 = tail call <8 x float> @llvm.x86.avx2.gather.d.ps.256(<8 x float> undef, i8* %arr.ptr, <8 x i32> %vix, <8 x float> <float 0xFFFFFFFFE0000000, float 0xFFFFFFFFE0000000, float 0xFFFFFFFFE0000000, float 0xFFFFFFFFE0000000, float 0xFFFFFFFFE0000000, float 0xFFFFFFFFE0000000, float 0xFFFFFFFFE0000000, float 0xFFFFFFFFE0000000>, i8 1) #2
+ store i8 1, i8* %t1.ptr, align 4
+
+ %v2 = tail call <8 x float> @llvm.x86.avx2.gather.d.ps.256(<8 x float> undef, i8* %arr.ptr, <8 x i32> %vix, <8 x float> <float 0xFFFFFFFFE0000000, float 0xFFFFFFFFE0000000, float 0xFFFFFFFFE0000000, float 0xFFFFFFFFE0000000, float 0xFFFFFFFFE0000000, float 0xFFFFFFFFE0000000, float 0xFFFFFFFFE0000000, float 0xFFFFFFFFE0000000>, i8 1) #2
+ %res = fadd <8 x float> %v1, %v2
+
+ ret <8 x float> %res
+}
+; CHECK: foo1
+; CHECK: llvm.x86.avx2.gather.d.ps.256
+; CHECK: store
+; CHECK: llvm.x86.avx2.gather.d.ps.256
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