[llvm] 19ad1cd - Recommit "[SCEV] Support clearing Block/LoopDispositions for a single value."
Florian Hahn via llvm-commits
llvm-commits at lists.llvm.org
Fri Oct 7 12:15:59 PDT 2022
Author: Florian Hahn
Date: 2022-10-07T20:15:44+01:00
New Revision: 19ad1cd5cea129056255e1193daa9107ef374e00
URL: https://github.com/llvm/llvm-project/commit/19ad1cd5cea129056255e1193daa9107ef374e00
DIFF: https://github.com/llvm/llvm-project/commit/19ad1cd5cea129056255e1193daa9107ef374e00.diff
LOG: Recommit "[SCEV] Support clearing Block/LoopDispositions for a single value."
This reverts commit 92f698f01fa0bb8967233a6391ada2d51849fa68.
The updated version of the patch includes handling for non-SCEVable
types. A test case has been added in ec86e9a99bca802.
Added:
Modified:
llvm/include/llvm/Analysis/ScalarEvolution.h
llvm/lib/Analysis/ScalarEvolution.cpp
llvm/lib/Transforms/Scalar/LoopDeletion.cpp
llvm/lib/Transforms/Scalar/LoopSink.cpp
llvm/lib/Transforms/Utils/LoopSimplify.cpp
Removed:
################################################################################
diff --git a/llvm/include/llvm/Analysis/ScalarEvolution.h b/llvm/include/llvm/Analysis/ScalarEvolution.h
index 83f8a9e94bfe6..580fef9f7a5d6 100644
--- a/llvm/include/llvm/Analysis/ScalarEvolution.h
+++ b/llvm/include/llvm/Analysis/ScalarEvolution.h
@@ -944,7 +944,7 @@ class ScalarEvolution {
///
/// We don't have a way to invalidate per-loop/per-block dispositions. Clear
/// and recompute is simpler.
- void forgetBlockAndLoopDispositions();
+ void forgetBlockAndLoopDispositions(Value *V = nullptr);
/// Determine the minimum number of zero bits that S is guaranteed to end in
/// (at every loop iteration). It is, at the same time, the minimum number
diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index ac36aba386682..189245ef10754 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -8384,9 +8384,39 @@ void ScalarEvolution::forgetValue(Value *V) {
void ScalarEvolution::forgetLoopDispositions() { LoopDispositions.clear(); }
-void ScalarEvolution::forgetBlockAndLoopDispositions() {
- BlockDispositions.clear();
- LoopDispositions.clear();
+void ScalarEvolution::forgetBlockAndLoopDispositions(Value *V) {
+ // Unless a specific value is passed to invalidation, completely clear both
+ // caches.
+ if (!V) {
+ BlockDispositions.clear();
+ LoopDispositions.clear();
+ return;
+ }
+
+ if (!isSCEVable(V->getType()))
+ return;
+
+ const SCEV *S = getExistingSCEV(V);
+ if (!S)
+ return;
+
+ // Invalidate the block and loop dispositions cached for S. Dispositions of
+ // S's users may change if S's disposition changes (i.e. a user may change to
+ // loop-invariant, if S changes to loop invariant), so also invalidate
+ // dispositions of S's users recursively.
+ SmallVector<const SCEV *, 8> Worklist = {S};
+ SmallPtrSet<const SCEV *, 8> Seen = {S};
+ while (!Worklist.empty()) {
+ const SCEV *Curr = Worklist.pop_back_val();
+ if (!LoopDispositions.erase(Curr) && !BlockDispositions.erase(S))
+ continue;
+
+ auto Users = SCEVUsers.find(Curr);
+ if (Users != SCEVUsers.end())
+ for (const auto *User : Users->second)
+ if (Seen.insert(User).second)
+ Worklist.push_back(User);
+ }
}
/// Get the exact loop backedge taken count considering all loop exits. A
diff --git a/llvm/lib/Transforms/Scalar/LoopDeletion.cpp b/llvm/lib/Transforms/Scalar/LoopDeletion.cpp
index d969126b3ad26..f19f53e8153d3 100644
--- a/llvm/lib/Transforms/Scalar/LoopDeletion.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopDeletion.cpp
@@ -90,22 +90,21 @@ static bool isLoopDead(Loop *L, ScalarEvolution &SE,
break;
if (Instruction *I = dyn_cast<Instruction>(incoming)) {
- if (!L->makeLoopInvariant(I, Changed, Preheader->getTerminator())) {
+ bool InstrMoved = false;
+ if (!L->makeLoopInvariant(I, InstrMoved, Preheader->getTerminator())) {
AllEntriesInvariant = false;
break;
}
- if (Changed) {
+ Changed |= InstrMoved;
+ if (InstrMoved) {
// Moving I to a
diff erent location may change its block disposition,
// so invalidate its SCEV.
- SE.forgetValue(I);
+ SE.forgetBlockAndLoopDispositions(I);
}
}
}
}
- if (Changed)
- SE.forgetLoopDispositions();
-
if (!AllEntriesInvariant || !AllOutgoingValuesSame)
return false;
diff --git a/llvm/lib/Transforms/Scalar/LoopSink.cpp b/llvm/lib/Transforms/Scalar/LoopSink.cpp
index 131af32e870db..ff937273428e4 100644
--- a/llvm/lib/Transforms/Scalar/LoopSink.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopSink.cpp
@@ -312,12 +312,13 @@ static bool sinkLoopInvariantInstructions(Loop &L, AAResults &AA, LoopInfo &LI,
if (!canSinkOrHoistInst(I, &AA, &DT, &L, MSSAU, false, LICMFlags))
continue;
if (sinkInstruction(L, I, ColdLoopBBs, LoopBlockNumber, LI, DT, BFI,
- &MSSAU))
+ &MSSAU)) {
Changed = true;
+ if (SE)
+ SE->forgetBlockAndLoopDispositions(&I);
+ }
}
- if (Changed && SE)
- SE->forgetLoopDispositions();
return Changed;
}
diff --git a/llvm/lib/Transforms/Utils/LoopSimplify.cpp b/llvm/lib/Transforms/Utils/LoopSimplify.cpp
index 16085f47449a5..f247a7eb33f87 100644
--- a/llvm/lib/Transforms/Utils/LoopSimplify.cpp
+++ b/llvm/lib/Transforms/Utils/LoopSimplify.cpp
@@ -647,20 +647,22 @@ static bool simplifyOneLoop(Loop *L, SmallVectorImpl<Loop *> &Worklist,
Instruction *Inst = &*I++;
if (Inst == CI)
continue;
+ bool InstInvariant = false;
if (!L->makeLoopInvariant(
- Inst, AnyInvariant,
+ Inst, InstInvariant,
Preheader ? Preheader->getTerminator() : nullptr, MSSAU)) {
AllInvariant = false;
break;
}
+ if (InstInvariant && SE) {
+ // The loop disposition of all SCEV expressions that depend on any
+ // hoisted values have also changed.
+ SE->forgetBlockAndLoopDispositions(Inst);
+ }
+ AnyInvariant |= InstInvariant;
}
- if (AnyInvariant) {
+ if (AnyInvariant)
Changed = true;
- // The loop disposition of all SCEV expressions that depend on any
- // hoisted values have also changed.
- if (SE)
- SE->forgetLoopDispositions();
- }
if (!AllInvariant) continue;
// The block has now been cleared of all instructions except for
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