Teach indvars to generate nsw/nuw flags when widening an induction variable.

Fixes PR16600.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186272 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Analysis/ScalarEvolutionExpander.cpp b/lib/Analysis/ScalarEvolutionExpander.cpp
index fcd7ce272a221c9468cd199e7bb07899449ad45d..0dd1043b1926164bf5c46f4c07a5165098de529f 100644 (file)
--- a/lib/Analysis/ScalarEvolutionExpander.cpp
+++ b/lib/Analysis/ScalarEvolutionExpander.cpp
@@ -1137,7 +1137,12 @@ SCEVExpander::getAddRecExprPHILiterally(const SCEVAddRecExpr *Normalized,
       IVIncInsertPos : Pred->getTerminator();
     Builder.SetInsertPoint(InsertPos);
     Value *IncV = expandIVInc(PN, StepV, L, ExpandTy, IntTy, useSubtract);
-
+    if (isa<OverflowingBinaryOperator>(IncV)) {
+      if (Normalized->getNoWrapFlags(SCEV::FlagNUW))
+        cast<BinaryOperator>(IncV)->setHasNoUnsignedWrap();
+      if (Normalized->getNoWrapFlags(SCEV::FlagNSW))
+        cast<BinaryOperator>(IncV)->setHasNoSignedWrap();
+    }
     PN->addIncoming(IncV, Pred);
   }
 

diff --git a/test/Transforms/IndVarSimplify/widen-nsw.ll b/test/Transforms/IndVarSimplify/widen-nsw.ll
new file mode 100644 (file)
index 0000000..56c3c0d
--- /dev/null
+++ b/test/Transforms/IndVarSimplify/widen-nsw.ll
@@ -0,0 +1,29 @@
+; RUN: opt < %s -indvars -S | FileCheck %s
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx"
+
+; CHECK-LABEL: @test1
+; CHECK: %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+define i32 @test1(i32* %a) #0 {
+entry:
+  br label %for.cond
+
+for.cond:                                         ; preds = %for.body, %entry
+  %sum.0 = phi i32 [ 0, %entry ], [ %add, %for.body ]
+  %i.0 = phi i32 [ 0, %entry ], [ %inc, %for.body ]
+  %cmp = icmp slt i32 %i.0, 1000
+  br i1 %cmp, label %for.body, label %for.end
+
+for.body:                                         ; preds = %for.cond
+  %idxprom = sext i32 %i.0 to i64
+  %arrayidx = getelementptr inbounds i32* %a, i64 %idxprom
+  %0 = load i32* %arrayidx, align 4
+  %add = add nsw i32 %sum.0, %0
+  %inc = add nsw i32 %i.0, 1
+  br label %for.cond
+
+for.end:                                          ; preds = %for.cond
+  ret i32 %sum.0
+}
+
+attributes #0 = { nounwind ssp uwtable "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf"="true" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "unsafe-fp-math"="false" "use-soft-float"="false" }