Add 'umax' similar to 'smax' SCEV. Closes PR2003.

Parse reversed smax and umax as smin and umin and express them with negative
or binary-not SCEVs (which are really just subtract under the hood).

Parse 'xor %x, -1' as (-1 - %x).

Remove dead code (ConstantInt::get always returns a ConstantInt).

Don't use getIntegerSCEV(-1, Ty). The first value is an int, then it gets
passed into a uint64_t. Instead, create the -1 directly from
ConstantInt::getAllOnesValue().


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@47360 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 10 insertions, 1 deletions

diff --git a/lib/Analysis/ScalarEvolutionExpander.cpp b/lib/Analysis/ScalarEvolutionExpander.cpp
index 3e05600bed..0a0327d925 100644
--- a/lib/Analysis/ScalarEvolutionExpander.cpp
+++ b/lib/Analysis/ScalarEvolutionExpander.cpp
@@ -220,6 +220,16 @@ Value *SCEVExpander::visitSMaxExpr(SCEVSMaxExpr *S) {
   return LHS;
 }
 
+Value *SCEVExpander::visitUMaxExpr(SCEVUMaxExpr *S) {
+  Value *LHS = expand(S->getOperand(0));
+  for (unsigned i = 1; i < S->getNumOperands(); ++i) {
+    Value *RHS = expand(S->getOperand(i));
+    Value *ICmp = new ICmpInst(ICmpInst::ICMP_UGT, LHS, RHS, "tmp", InsertPt);
+    LHS = new SelectInst(ICmp, LHS, RHS, "umax", InsertPt);
+  }
+  return LHS;
+}
+
 Value *SCEVExpander::expand(SCEV *S) {
   // Check to see if we already expanded this.
   std::map<SCEVHandle, Value*>::iterator I = InsertedExpressions.find(S);
@@ -230,4 +240,3 @@ Value *SCEVExpander::expand(SCEV *S) {
   InsertedExpressions[S] = V;
   return V;
 }
-