[PATCH] D138228: [LoopPeel] Expose ValueMap of last peeled iteration. NFC

[Anna Thomas via Phabricator via llvm-commits]

anna created this revision.
anna added reviewers: nikic, fhahn, mkazantsev, apilipenko.
Herald added subscribers: zzheng, hiraditya.
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The value map of last peeled iteration is computed within peelLoop API.
This patch exposes it for callers of peelLoop.
While this is not currently used by upstream passes, we have a usecase
downstream which benefits from this API update. Future users of peelLoop
can also use the ValueMap if needed.

Similar value maps are exposed by other loop utilities such as loop
cloning.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D138228

Files:
  llvm/include/llvm/Transforms/Utils/LoopPeel.h
  llvm/lib/Transforms/Scalar/LoopFuse.cpp
  llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
  llvm/lib/Transforms/Utils/LoopPeel.cpp


Index: llvm/lib/Transforms/Utils/LoopPeel.cpp
===================================================================
--- llvm/lib/Transforms/Utils/LoopPeel.cpp
+++ llvm/lib/Transforms/Utils/LoopPeel.cpp
@@ -741,7 +741,7 @@
 /// optimizations.
 bool llvm::peelLoop(Loop *L, unsigned PeelCount, LoopInfo *LI,
                     ScalarEvolution *SE, DominatorTree &DT, AssumptionCache *AC,
-                    bool PreserveLCSSA) {
+                    bool PreserveLCSSA, ValueToValueMapTy &LVMap) {
   assert(PeelCount > 0 && "Attempt to peel out zero iterations?");
   assert(canPeel(L) && "Attempt to peel a loop which is not peelable?");
 
@@ -833,8 +833,6 @@
   InsertBot->setName(Header->getName() + ".peel.next");
   NewPreHeader->setName(PreHeader->getName() + ".peel.newph");
 
-  ValueToValueMapTy LVMap;
-
   Instruction *LatchTerm =
       cast<Instruction>(cast<BasicBlock>(Latch)->getTerminator());
 
Index: llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
+++ llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
@@ -1289,7 +1289,8 @@
              << " iterations";
     });
 
-    if (peelLoop(L, PP.PeelCount, LI, &SE, DT, &AC, PreserveLCSSA)) {
+    ValueToValueMapTy VMap;
+    if (peelLoop(L, PP.PeelCount, LI, &SE, DT, &AC, PreserveLCSSA, VMap)) {
       simplifyLoopAfterUnroll(L, true, LI, &SE, &DT, &AC, &TTI);
       // If the loop was peeled, we already "used up" the profile information
       // we had, so we don't want to unroll or peel again.
Index: llvm/lib/Transforms/Scalar/LoopFuse.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/LoopFuse.cpp
+++ llvm/lib/Transforms/Scalar/LoopFuse.cpp
@@ -767,7 +767,8 @@
     LLVM_DEBUG(dbgs() << "Attempting to peel first " << PeelCount
                       << " iterations of the first loop. \n");
 
-    FC0.Peeled = peelLoop(FC0.L, PeelCount, &LI, &SE, DT, &AC, true);
+    ValueToValueMapTy VMap;
+    FC0.Peeled = peelLoop(FC0.L, PeelCount, &LI, &SE, DT, &AC, true, VMap);
     if (FC0.Peeled) {
       LLVM_DEBUG(dbgs() << "Done Peeling\n");
 
Index: llvm/include/llvm/Transforms/Utils/LoopPeel.h
===================================================================
--- llvm/include/llvm/Transforms/Utils/LoopPeel.h
+++ llvm/include/llvm/Transforms/Utils/LoopPeel.h
@@ -15,13 +15,17 @@
 #define LLVM_TRANSFORMS_UTILS_LOOPPEEL_H
 
 #include "llvm/Analysis/TargetTransformInfo.h"
+#include "llvm/Transforms/Utils/ValueMapper.h"
 
 namespace llvm {
 
 bool canPeel(Loop *L);
 
+/// VMap is the value-map that maps instructions from the original loop to
+/// instructions in the last peeled-off iteration.
 bool peelLoop(Loop *L, unsigned PeelCount, LoopInfo *LI, ScalarEvolution *SE,
-              DominatorTree &DT, AssumptionCache *AC, bool PreserveLCSSA);
+              DominatorTree &DT, AssumptionCache *AC, bool PreserveLCSSA,
+              ValueToValueMapTy &VMap);
 
 TargetTransformInfo::PeelingPreferences
 gatherPeelingPreferences(Loop *L, ScalarEvolution &SE,


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