[llvm] 7629b2a - [LI] Add a cover function for checking if a loop is mustprogress [nfc]

[Philip Reames via llvm-commits]

Author: Philip Reames
Date: 2021-06-10T13:37:32-07:00
New Revision: 7629b2a09c169bfd7f7295deb3678f3fa7755eee

URL: https://github.com/llvm/llvm-project/commit/7629b2a09c169bfd7f7295deb3678f3fa7755eee
DIFF: https://github.com/llvm/llvm-project/commit/7629b2a09c169bfd7f7295deb3678f3fa7755eee.diff

LOG: [LI] Add a cover function for checking if a loop is mustprogress [nfc]

Essentially, the cover function simply combines the loop level check and the function level scope into one call.  This simplifies several callers and is (subjectively) less error prone.

Added: 
    

Modified: 
    llvm/include/llvm/Analysis/LoopInfo.h
    llvm/lib/Analysis/LoopInfo.cpp
    llvm/lib/Analysis/ScalarEvolution.cpp
    llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
    llvm/lib/Transforms/Utils/LoopUtils.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/include/llvm/Analysis/LoopInfo.h b/llvm/include/llvm/Analysis/LoopInfo.h
index 8a8ee060e65ea..6e149b5d14fa9 100644
--- a/llvm/include/llvm/Analysis/LoopInfo.h
+++ b/llvm/include/llvm/Analysis/LoopInfo.h
@@ -1311,8 +1311,14 @@ Optional<const MDOperand *> findStringMetadataForLoop(const Loop *TheLoop,
                                                       StringRef Name);
 
 /// Look for the loop attribute that requires progress within the loop.
+/// Note: Most consumers probably want "isMustProgress" which checks
+/// the containing function attribute too.
 bool hasMustProgress(const Loop *L);
 
+/// Return true if this loop can be assumed to make progress.  (i.e. can't
+/// be infinite without side effects without also being undefined)
+bool isMustProgress(const Loop *L);
+
 /// Return whether an MDNode might represent an access group.
 ///
 /// Access group metadata nodes have to be distinct and empty. Being

diff  --git a/llvm/lib/Analysis/LoopInfo.cpp b/llvm/lib/Analysis/LoopInfo.cpp
index 5a2b7ff46cbbb..f45cc12d46302 100644
--- a/llvm/lib/Analysis/LoopInfo.cpp
+++ b/llvm/lib/Analysis/LoopInfo.cpp
@@ -1108,6 +1108,10 @@ bool llvm::hasMustProgress(const Loop *L) {
   return getBooleanLoopAttribute(L, LLVMLoopMustProgress);
 }
 
+bool llvm::isMustProgress(const Loop *L) {
+  return L->getHeader()->getParent()->mustProgress() || hasMustProgress(L);
+}
+
 bool llvm::isValidAsAccessGroup(MDNode *Node) {
   return Node->getNumOperands() == 0 && Node->isDistinct();
 }

diff  --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index 06aa6cb49ae39..275fad4acb2b2 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -6579,14 +6579,10 @@ ScalarEvolution::getLoopProperties(const Loop *L) {
 }
 
 bool ScalarEvolution::loopIsFiniteByAssumption(const Loop *L) {
-  if (!L->getHeader()->getParent()->mustProgress() &&
-      !hasMustProgress(L))
-    return false;
-
-  // A loop without side effects must be finite.
+  // A mustprogress loop without side effects must be finite.
   // TODO: The check used here is very conservative.  It's only *specific*
   // side effects which are well defined in infinite loops.
-  return loopHasNoSideEffects(L);
+  return isMustProgress(L) && loopHasNoSideEffects(L);
 }
 
 const SCEV *ScalarEvolution::createSCEV(Value *V) {

diff  --git a/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp b/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
index be95ac1844287..aed9994399d2e 100644
--- a/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
@@ -2535,8 +2535,7 @@ static bool detectShiftUntilZeroIdiom(Loop *CurLoop, ScalarEvolution *SE,
   // right-shift, iff the sign bit was set, the value will never become zero,
   // and the loop may never finish.
   if (ValShifted->getOpcode() == Instruction::AShr &&
-      !CurLoop->getHeader()->getParent()->mustProgress() &&
-      !hasMustProgress(CurLoop) && !SE->isKnownNonNegative(SE->getSCEV(Val))) {
+      !isMustProgress(CurLoop) && !SE->isKnownNonNegative(SE->getSCEV(Val))) {
     LLVM_DEBUG(dbgs() << DEBUG_TYPE " Can not prove the loop is finite.\n");
     return false;
   }

diff  --git a/llvm/lib/Transforms/Utils/LoopUtils.cpp b/llvm/lib/Transforms/Utils/LoopUtils.cpp
index 761960f0da62b..95ae7dbb3ddc9 100644
--- a/llvm/lib/Transforms/Utils/LoopUtils.cpp
+++ b/llvm/lib/Transforms/Utils/LoopUtils.cpp
@@ -1781,8 +1781,7 @@ Optional<IVConditionInfo> llvm::hasPartialIVCondition(Loop &L,
 
     // We could also allow loops with known trip counts without mustprogress,
     // but ScalarEvolution may not be available.
-    Info.PathIsNoop &=
-        L.getHeader()->getParent()->mustProgress() || hasMustProgress(&L);
+    Info.PathIsNoop &= isMustProgress(&L);
 
     // If the path is considered a no-op so far, check if it reaches a
     // single exit block without any phis. This ensures no values from the