[llvm] 3a54b6a - [MemDep] Use BatchAA when computing pointer dependencies
Nikita Popov via llvm-commits
llvm-commits at lists.llvm.org
Tue Aug 25 12:34:44 PDT 2020
Author: Nikita Popov
Date: 2020-08-25T21:34:34+02:00
New Revision: 3a54b6a4b71c21cf3bab4f132cbc2904fb9d997e
URL: https://github.com/llvm/llvm-project/commit/3a54b6a4b71c21cf3bab4f132cbc2904fb9d997e
DIFF: https://github.com/llvm/llvm-project/commit/3a54b6a4b71c21cf3bab4f132cbc2904fb9d997e.diff
LOG: [MemDep] Use BatchAA when computing pointer dependencies
We're not changing IR while running a single MemDep query, so it's
safe to cache alias analysis results using BatchAA. This adds BatchAA
usage to getSimplePointerDependencyFrom(), which is non-intrusive --
covering larger parts (like a whole processNonLocalLoad query) is
also possible, but requires threading BatchAA through a bunch of APIs.
For the ThinLTO configuration, this is a 1% geomean improvement on CTMark.
Differential Revision: https://reviews.llvm.org/D85583
Added:
Modified:
llvm/lib/Analysis/MemoryDependenceAnalysis.cpp
Removed:
################################################################################
diff --git a/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp b/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp
index 7f3de0fcf140..2428d57d2809 100644
--- a/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp
+++ b/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp
@@ -362,6 +362,8 @@ MemoryDependenceResults::getInvariantGroupPointerDependency(LoadInst *LI,
MemDepResult MemoryDependenceResults::getSimplePointerDependencyFrom(
const MemoryLocation &MemLoc, bool isLoad, BasicBlock::iterator ScanIt,
BasicBlock *BB, Instruction *QueryInst, unsigned *Limit) {
+ // We can batch AA queries, because IR does not change during a MemDep query.
+ BatchAAResults BatchAA(AA);
bool isInvariantLoad = false;
unsigned DefaultLimit = getDefaultBlockScanLimit();
@@ -445,7 +447,7 @@ MemDepResult MemoryDependenceResults::getSimplePointerDependencyFrom(
// pointer, not on query pointers that are indexed off of them. It'd
// be nice to handle that at some point (the right approach is to use
// GetPointerBaseWithConstantOffset).
- if (AA.isMustAlias(MemoryLocation(II->getArgOperand(1)), MemLoc))
+ if (BatchAA.isMustAlias(MemoryLocation(II->getArgOperand(1)), MemLoc))
return MemDepResult::getDef(II);
continue;
}
@@ -485,7 +487,7 @@ MemDepResult MemoryDependenceResults::getSimplePointerDependencyFrom(
MemoryLocation LoadLoc = MemoryLocation::get(LI);
// If we found a pointer, check if it could be the same as our pointer.
- AliasResult R = AA.alias(LoadLoc, MemLoc);
+ AliasResult R = BatchAA.alias(LoadLoc, MemLoc);
if (isLoad) {
if (R == NoAlias)
@@ -516,7 +518,7 @@ MemDepResult MemoryDependenceResults::getSimplePointerDependencyFrom(
continue;
// Stores don't alias loads from read-only memory.
- if (AA.pointsToConstantMemory(LoadLoc))
+ if (BatchAA.pointsToConstantMemory(LoadLoc))
continue;
// Stores depend on may/must aliased loads.
@@ -547,7 +549,7 @@ MemDepResult MemoryDependenceResults::getSimplePointerDependencyFrom(
// If alias analysis can tell that this store is guaranteed to not modify
// the query pointer, ignore it. Use getModRefInfo to handle cases where
// the query pointer points to constant memory etc.
- if (!isModOrRefSet(AA.getModRefInfo(SI, MemLoc)))
+ if (!isModOrRefSet(BatchAA.getModRefInfo(SI, MemLoc)))
continue;
// Ok, this store might clobber the query pointer. Check to see if it is
@@ -556,7 +558,7 @@ MemDepResult MemoryDependenceResults::getSimplePointerDependencyFrom(
MemoryLocation StoreLoc = MemoryLocation::get(SI);
// If we found a pointer, check if it could be the same as our pointer.
- AliasResult R = AA.alias(StoreLoc, MemLoc);
+ AliasResult R = BatchAA.alias(StoreLoc, MemLoc);
if (R == NoAlias)
continue;
@@ -575,7 +577,7 @@ MemDepResult MemoryDependenceResults::getSimplePointerDependencyFrom(
// handled by BasicAA.
if (isa<AllocaInst>(Inst) || isNoAliasFn(Inst, &TLI)) {
const Value *AccessPtr = getUnderlyingObject(MemLoc.Ptr);
- if (AccessPtr == Inst || AA.isMustAlias(Inst, AccessPtr))
+ if (AccessPtr == Inst || BatchAA.isMustAlias(Inst, AccessPtr))
return MemDepResult::getDef(Inst);
}
@@ -592,9 +594,10 @@ MemDepResult MemoryDependenceResults::getSimplePointerDependencyFrom(
continue;
// See if this instruction (e.g. a call or vaarg) mod/ref's the pointer.
- ModRefInfo MR = AA.getModRefInfo(Inst, MemLoc);
+ ModRefInfo MR = BatchAA.getModRefInfo(Inst, MemLoc);
// If necessary, perform additional analysis.
if (isModAndRefSet(MR))
+ // TODO: Support callCapturesBefore() on BatchAAResults.
MR = AA.callCapturesBefore(Inst, MemLoc, &DT);
switch (clearMust(MR)) {
case ModRefInfo::NoModRef:
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