[SCEV] Opportunistically interpret unsigned constraints as signed
Summary:
An unsigned comparision is equivalent to is corresponding signed version
if both the operands being compared are positive. Teach SCEV to use
this fact when profitable.
Reviewers: atrick, hfinkel, reames, nlewycky
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D13687
llvm-svn: 251051
diff --git a/llvm/test/Transforms/IndVarSimplify/eliminate-comparison.ll b/llvm/test/Transforms/IndVarSimplify/eliminate-comparison.ll
index 563ea3a..eb60bac 100644
--- a/llvm/test/Transforms/IndVarSimplify/eliminate-comparison.ll
+++ b/llvm/test/Transforms/IndVarSimplify/eliminate-comparison.ll
@@ -535,5 +535,55 @@
ret void
}
+define void @func_24(i32* %length.ptr) {
+; CHECK-LABEL: @func_24(
+ entry:
+ %length = load i32, i32* %length.ptr, !range !0
+ %entry.cond = icmp ult i32 4, %length
+ br i1 %entry.cond, label %loop, label %leave
+
+ loop:
+; CHECK: loop:
+ %iv = phi i32 [ 4, %entry ], [ %iv.inc, %be ]
+ %iv.inc = add i32 %iv, 1
+ %range.check = icmp slt i32 %iv, %length
+ br i1 %range.check, label %be, label %leave
+; CHECK: br i1 true, label %be, label %leave.loopexit
+; CHECK: be:
+
+ be:
+ call void @side_effect()
+ %be.cond = icmp slt i32 %iv.inc, %length
+ br i1 %be.cond, label %loop, label %leave
+
+ leave:
+ ret void
+}
+
+define void @func_25(i32* %init.ptr) {
+; CHECK-LABEL: @func_25(
+ entry:
+ %init = load i32, i32* %init.ptr, !range !0
+ %entry.cond = icmp ugt i32 %init, 4
+ br i1 %entry.cond, label %loop, label %leave
+
+ loop:
+; CHECK: loop:
+ %iv = phi i32 [ %init, %entry ], [ %iv.dec, %be ]
+ %iv.dec = add i32 %iv, -1
+ %range.check = icmp sgt i32 %iv, 4
+ br i1 %range.check, label %be, label %leave
+; CHECK: br i1 true, label %be, label %leave.loopexit
+; CHECK: be:
+
+ be:
+ call void @side_effect()
+ %be.cond = icmp sgt i32 %iv.dec, 4
+ br i1 %be.cond, label %loop, label %leave
+
+ leave:
+ ret void
+}
+
!0 = !{i32 0, i32 2147483647}