Refine the change in r52258 for avoiding use-before-def conditions

when changing the stride of a comparison so that it's slightly
more precise, by having it scan the instruction list to determine
if there is a use of the condition after the point where the
condition will be inserted.

llvm-svn: 52371

1 files changed, 24 insertions, 0 deletions

diff --git a/llvm/test/Transforms/LoopStrengthReduce/change-compare-stride-trickiness-0.ll b/llvm/test/Transforms/LoopStrengthReduce/change-compare-stride-trickiness-0.ll
new file mode 100644
index 00000000000..33b05221511
--- /dev/null
+++ b/llvm/test/Transforms/LoopStrengthReduce/change-compare-stride-trickiness-0.ll
@@ -0,0 +1,24 @@
+; RUN: llvm-as < %s | llc --x86-asm-syntax=att | grep {cmpl	\$4}
+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"
+target triple = "x86_64-apple-darwin9"
+
+; This is like change-compare-stride-trickiness-1.ll except the comparison
+; happens before the relevant use, so the comparison stride can't be
+; easily changed.
+
+define void @foo() {
+entry:
+	br label %loop
+
+loop:
+	%indvar = phi i32 [ 0, %entry ], [ %i.2.0.us1534, %loop ]		; <i32> [#uses=1]
+	%i.2.0.us1534 = add i32 %indvar, 1		; <i32> [#uses=3]
+	%tmp611.us1535 = icmp eq i32 %i.2.0.us1534, 4		; <i1> [#uses=2]
+	%tmp623.us1538 = select i1 %tmp611.us1535, i32 6, i32 0		; <i32> [#uses=0]
+	%tmp628.us1540 = shl i32 %i.2.0.us1534, 1		; <i32> [#uses=1]
+	%tmp645646647.us1547 = sext i32 %tmp628.us1540 to i64		; <i64> [#uses=0]
+	br i1 %tmp611.us1535, label %exit, label %loop
+
+exit:
+	ret void
+}