Fix a corner case in the new indvars promotion logic: if there

are multiple IV's in a loop, some of them may under go signed
or unsigned wrapping even if the IV that's used in the loop
exit condition doesn't. Restrict sign-extension-elimination
and zero-extension-elimination to only those that operate on
the original loop-controlling IV.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@64866 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 38 insertions, 0 deletions

diff --git a/test/Transforms/IndVarSimplify/preserve-signed-wrap.ll b/test/Transforms/IndVarSimplify/preserve-signed-wrap.ll
new file mode 100644
index 0000000..0a91ec8
--- /dev/null
+++ b/test/Transforms/IndVarSimplify/preserve-signed-wrap.ll
@@ -0,0 +1,38 @@
+; RUN: llvm-as < %s | opt -indvars | llvm-dis > %t
+; RUN: grep sext %t | count 1
+; RUN: grep phi %t | count 1
+; RUN: grep {phi i64} %t
+
+; Indvars should insert a 64-bit induction variable to eliminate the
+; sext for the addressing, however it shouldn't eliminate the sext
+; on the other phi, since that value undergoes signed wrapping.
+
+define void @foo(i32* nocapture %d, i32 %n) nounwind {
+entry:
+	%0 = icmp sgt i32 %n, 0		; <i1> [#uses=1]
+	br i1 %0, label %bb.nph, label %return
+
+bb.nph:		; preds = %entry
+	br label %bb
+
+bb:		; preds = %bb1, %bb.nph
+	%i.02 = phi i32 [ %5, %bb1 ], [ 0, %bb.nph ]		; <i32> [#uses=2]
+	%p.01 = phi i8 [ %4, %bb1 ], [ -1, %bb.nph ]		; <i8> [#uses=2]
+	%1 = sext i8 %p.01 to i32		; <i32> [#uses=1]
+	%2 = sext i32 %i.02 to i64		; <i64> [#uses=1]
+	%3 = getelementptr i32* %d, i64 %2		; <i32*> [#uses=1]
+	store i32 %1, i32* %3, align 4
+	%4 = add i8 %p.01, 1		; <i8> [#uses=1]
+	%5 = add i32 %i.02, 1		; <i32> [#uses=2]
+	br label %bb1
+
+bb1:		; preds = %bb
+	%6 = icmp slt i32 %5, %n		; <i1> [#uses=1]
+	br i1 %6, label %bb, label %bb1.return_crit_edge
+
+bb1.return_crit_edge:		; preds = %bb1
+	br label %return
+
+return:		; preds = %bb1.return_crit_edge, %entry
+	ret void
+}