// TODO:
// Try harder to find if the source integer type has less significant bits.
- // For example, compute number of sign bits or compute low bit mask.
+ // For example, compute number of sign bits.
KnownBits SrcKnown = IC.computeKnownBits(Src, 0, &I);
- int LowBits =
- (int)SrcTy->getScalarSizeInBits() - SrcKnown.countMinLeadingZeros();
- if (LowBits <= DestNumSigBits)
+ int SigBits = (int)SrcTy->getScalarSizeInBits() -
+ SrcKnown.countMinLeadingZeros() -
+ SrcKnown.countMinTrailingZeros();
+ if (SigBits <= DestNumSigBits)
return true;
return false;
ret i25 %C
}
-define i25 @overflow_masked_input(i25 %A) {
-; CHECK-LABEL: @overflow_masked_input(
-; CHECK-NEXT: [[M:%.*]] = and i25 [[A:%.*]], -16777216
-; CHECK-NEXT: [[B:%.*]] = uitofp i25 [[M]] to float
-; CHECK-NEXT: [[C:%.*]] = fptoui float [[B]] to i25
-; CHECK-NEXT: ret i25 [[C]]
+define i25 @consider_lowbits_masked_input(i25 %A) {
+; CHECK-LABEL: @consider_lowbits_masked_input(
+; CHECK-NEXT: [[M:%.*]] = and i25 [[A:%.*]], -16777214
+; CHECK-NEXT: ret i25 [[M]]
;
- %m = and i25 %A, 16777216 ; Negative test - intermediate 16777216 (= 1 << 24)
+ %m = and i25 %A, 16777218 ; Make use of the low zero bits - intermediate 16777218 (= 1 << 24 + 2)
%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 i32 @overflow_masked_input(i32 %A) {
+; CHECK-LABEL: @overflow_masked_input(
+; CHECK-NEXT: [[M:%.*]] = and i32 [[A:%.*]], 16777217
+; CHECK-NEXT: [[B:%.*]] = uitofp i32 [[M]] to float
+; CHECK-NEXT: [[C:%.*]] = fptoui float [[B]] to i32
+; CHECK-NEXT: ret i32 [[C]]
+;
+ %m = and i32 %A, 16777217 ; Negative test - intermediate 16777217 (= 1 << 24 + 1)
+ %B = uitofp i32 %m to float
+ %C = fptoui float %B to i32
+ ret i32 %C
+}
+
+; 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]]
+; CHECK-NEXT: ret i25 [[M]]
;
%m = and i25 %A, -2
%B = uitofp i25 %m to float