[PATCH] D77538: [Alignment][NFC] Assume AlignmentFromAssumptions::getNewAlignment is always set.

[Guillaume Chatelet via Phabricator via llvm-commits]

gchatelet created this revision.
gchatelet added a reviewer: courbet.
Herald added subscribers: llvm-commits, hiraditya.
Herald added a project: LLVM.

In D77454 <https://reviews.llvm.org/D77454> we explain that `LoadInst` and `StoreInst` always have their alignment defined.
This allows to work backward here and to infer that `getNewAlignment` does not need to return `0` in case of failure.
Returning `1` also works since it needs to be greater than the Load/Store alignment which is a least `1`.

This is patch is part of a series to introduce an Alignment type.
See this thread for context: http://lists.llvm.org/pipermail/llvm-dev/2019-July/133851.html
See this patch for the introduction of the type: https://reviews.llvm.org/D64790


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D77538

Files:
  llvm/lib/Transforms/Scalar/AlignmentFromAssumptions.cpp


Index: llvm/lib/Transforms/Scalar/AlignmentFromAssumptions.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/AlignmentFromAssumptions.cpp
+++ llvm/lib/Transforms/Scalar/AlignmentFromAssumptions.cpp
@@ -321,29 +321,28 @@
 
   while (!WorkList.empty()) {
     Instruction *J = WorkList.pop_back_val();
-
     if (LoadInst *LI = dyn_cast<LoadInst>(J)) {
-      unsigned NewAlignment = getNewAlignment(AASCEV, AlignSCEV, OffSCEV,
-        LI->getPointerOperand(), SE);
+      Align NewAlignment = assumeAligned(getNewAlignment(
+          AASCEV, AlignSCEV, OffSCEV, LI->getPointerOperand(), SE));
 
-      if (NewAlignment > LI->getAlignment()) {
-        LI->setAlignment(MaybeAlign(NewAlignment));
+      if (NewAlignment > *LI->getAlign()) {
+        LI->setAlignment(NewAlignment);
         ++NumLoadAlignChanged;
       }
     } else if (StoreInst *SI = dyn_cast<StoreInst>(J)) {
-      unsigned NewAlignment = getNewAlignment(AASCEV, AlignSCEV, OffSCEV,
-        SI->getPointerOperand(), SE);
+      Align NewAlignment = assumeAligned(getNewAlignment(
+          AASCEV, AlignSCEV, OffSCEV, SI->getPointerOperand(), SE));
 
-      if (NewAlignment > SI->getAlignment()) {
-        SI->setAlignment(MaybeAlign(NewAlignment));
+      if (NewAlignment > *SI->getAlign()) {
+        SI->setAlignment(NewAlignment);
         ++NumStoreAlignChanged;
       }
     } else if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(J)) {
-      unsigned NewDestAlignment = getNewAlignment(AASCEV, AlignSCEV, OffSCEV,
-        MI->getDest(), SE);
+      Align NewDestAlignment = assumeAligned(
+          getNewAlignment(AASCEV, AlignSCEV, OffSCEV, MI->getDest(), SE));
 
       LLVM_DEBUG(dbgs() << "\tmem inst: " << NewDestAlignment << "\n";);
-      if (NewDestAlignment > MI->getDestAlignment()) {
+      if (NewDestAlignment > *MI->getDestAlign()) {
         MI->setDestAlignment(NewDestAlignment);
         ++NumMemIntAlignChanged;
       }
@@ -351,12 +350,12 @@
       // For memory transfers, there is also a source alignment that
       // can be set.
       if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(MI)) {
-        unsigned NewSrcAlignment = getNewAlignment(AASCEV, AlignSCEV, OffSCEV,
-          MTI->getSource(), SE);
+        Align NewSrcAlignment = assumeAligned(
+            getNewAlignment(AASCEV, AlignSCEV, OffSCEV, MTI->getSource(), SE));
 
         LLVM_DEBUG(dbgs() << "\tmem trans: " << NewSrcAlignment << "\n";);
 
-        if (NewSrcAlignment > MTI->getSourceAlignment()) {
+        if (NewSrcAlignment > *MTI->getSourceAlign()) {
           MTI->setSourceAlignment(NewSrcAlignment);
           ++NumMemIntAlignChanged;
         }


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