Extend ScalarEvolution's multiple-exit support to compute exact

trip counts in more cases.

Generalize ScalarEvolution's isLoopGuardedByCond code to recognize
And and Or conditions, splitting the code out into an
isNecessaryCond helper function so that it can evaluate Ands and Ors
recursively, and make SCEVExpander be much more aggressive about
hoisting instructions out of loops.

test/CodeGen/X86/pr3495.ll has an additional instruction now, but
it appears to be due to an arbitrary register allocation difference.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@74048 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 2 insertions, 10 deletions

diff --git a/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
index 312b957948..a877c4ea03 100644
--- a/lib/Transforms/Scalar/LoopStrengthReduce.cpp
+++ b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
@@ -409,16 +409,8 @@ Value *BasedUser::InsertCodeForBaseAtPosition(const SCEV* const &NewBase,
 
   const SCEV* NewValSCEV = SE->getUnknown(Base);
 
-  // If there is no immediate value, skip the next part.
-  if (!Imm->isZero()) {
-    // If we are inserting the base and imm values in the same block, make sure
-    // to adjust the IP position if insertion reused a result.
-    if (IP == BaseInsertPt)
-      IP = Rewriter.getInsertionPoint();
-
-    // Always emit the immediate (if non-zero) into the same block as the user.
-    NewValSCEV = SE->getAddExpr(NewValSCEV, Imm);
-  }
+  // Always emit the immediate into the same block as the user.
+  NewValSCEV = SE->getAddExpr(NewValSCEV, Imm);
 
   return Rewriter.expandCodeFor(NewValSCEV, Ty, IP);
 }