[InstCombine] add tests for known bits before FP casts; NFC
diff --git a/llvm/test/Transforms/InstCombine/sitofp.ll b/llvm/test/Transforms/InstCombine/sitofp.ll
index 1491547..57431b9 100644
--- a/llvm/test/Transforms/InstCombine/sitofp.ll
+++ b/llvm/test/Transforms/InstCombine/sitofp.ll
@@ -216,3 +216,32 @@
ret i55 %C
}
+; TODO: The mask guarantees that the input is small enough to eliminate the FP casts.
+
+define i25 @masked_input(i25 %A) {
+; CHECK-LABEL: @masked_input(
+; CHECK-NEXT: [[M:%.*]] = and i25 [[A:%.*]], 65535
+; CHECK-NEXT: [[B:%.*]] = uitofp i25 [[M]] to float
+; CHECK-NEXT: [[C:%.*]] = fptoui float [[B]] to i25
+; CHECK-NEXT: ret i25 [[C]]
+;
+ %m = and i25 %A, 65535
+ %B = uitofp i25 %m to float
+ %C = fptoui float %B to i25
+ ret i25 %C
+}
+
+; TODO: Clear the low bit - guarantees that the input is converted to FP without rounding.
+
+define i25 @low_masked_input(i25 %A) {
+; CHECK-LABEL: @low_masked_input(
+; CHECK-NEXT: [[M:%.*]] = and i25 [[A:%.*]], -2
+; CHECK-NEXT: [[B:%.*]] = uitofp i25 [[M]] to float
+; CHECK-NEXT: [[C:%.*]] = fptoui float [[B]] to i25
+; CHECK-NEXT: ret i25 [[C]]
+;
+ %m = and i25 %A, -2
+ %B = uitofp i25 %m to float
+ %C = fptoui float %B to i25
+ ret i25 %C
+}