Teach ComputeNumSignBits about signed reminder.

This optimization a continuation of r231140 that reasoned about signed div.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231433 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 21 insertions, 0 deletions

diff --git a/test/Transforms/InstCombine/intrinsics.ll b/test/Transforms/InstCombine/intrinsics.ll
index cfdda9405a8..539628a31be 100644
--- a/test/Transforms/InstCombine/intrinsics.ll
+++ b/test/Transforms/InstCombine/intrinsics.ll
@@ -386,3 +386,24 @@ entry:
   ret i1 %obit
 }
 
+; CHECK-LABEL: @overflow_mod_mul(
+; CHECK: ret i1 false
+define i1 @overflow_mod_mul(i32 %v1, i32 %v2) nounwind {
+entry:
+  %rem = srem i32 %v1, 1000
+  %t = call %ov.result.32 @llvm.smul.with.overflow.i32(i32 %rem, i32 %rem)
+  %obit = extractvalue %ov.result.32 %t, 1
+  ret i1 %obit
+}
+
+; CHECK-LABEL: @overflow_mod_overflow_mul(
+; CHECK-NOT: ret i1 false
+define i1 @overflow_mod_overflow_mul(i32 %v1, i32 %v2) nounwind {
+entry:
+  %rem = srem i32 %v1, 65537
+  ; This may overflow because the result of the mul operands may be greater than 16bits
+  ; and the result greater than 32.
+  %t = call %ov.result.32 @llvm.smul.with.overflow.i32(i32 %rem, i32 %rem)
+  %obit = extractvalue %ov.result.32 %t, 1
+  ret i1 %obit
+}