[SCEVExpander] Make CanonicalMode handing in isSafeToExpand() more robust (PR50506)

isSafeToExpand() for addrecs depends on whether the SCEVExpander
will be used in CanonicalMode. At least one caller currently gets
this wrong, resulting in PR50506.

Fix this by a) making the CanonicalMode argument on the freestanding
functions required and b) adding member functions on SCEVExpander
that automatically take the SCEVExpander mode into account. We can
use the latter variant nearly everywhere, and thus make sure that
there is no chance of CanonicalMode mismatch.

Fixes https://github.com/llvm/llvm-project/issues/50506.

Differential Revision: https://reviews.llvm.org/D129630

1 files changed, 2 insertions, 2 deletions

diff --git a/llvm/lib/Transforms/Utils/LoopUtils.cpp b/llvm/lib/Transforms/Utils/LoopUtils.cpp
index 82f993b..4119d8c 100644
--- a/llvm/lib/Transforms/Utils/LoopUtils.cpp
+++ b/llvm/lib/Transforms/Utils/LoopUtils.cpp
@@ -1357,7 +1357,7 @@ int llvm::rewriteLoopExitValues(Loop *L, LoopInfo *LI, TargetLibraryInfo *TLI,
         const SCEV *ExitValue = SE->getSCEVAtScope(Inst, L->getParentLoop());
         if (isa<SCEVCouldNotCompute>(ExitValue) ||
             !SE->isLoopInvariant(ExitValue, L) ||
-            !isSafeToExpand(ExitValue, *SE)) {
+            !Rewriter.isSafeToExpand(ExitValue)) {
           // TODO: This should probably be sunk into SCEV in some way; maybe a
           // getSCEVForExit(SCEV*, L, ExitingBB)?  It can be generalized for
           // most SCEV expressions and other recurrence types (e.g. shift
@@ -1370,7 +1370,7 @@ int llvm::rewriteLoopExitValues(Loop *L, LoopInfo *LI, TargetLibraryInfo *TLI,
               ExitValue = AddRec->evaluateAtIteration(ExitCount, *SE);
           if (isa<SCEVCouldNotCompute>(ExitValue) ||
               !SE->isLoopInvariant(ExitValue, L) ||
-              !isSafeToExpand(ExitValue, *SE))
+              !Rewriter.isSafeToExpand(ExitValue))
             continue;
         }