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[DemandedBits][BDCE] Add support for min/max intrinsics

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Add DemandedBits / BDCE support for min/max intrinsics: If the low
bits are not demanded in the result, they also aren't demanded in
the operands.

Differential Revision: https://reviews.llvm.org/D87161
This commit is contained in:
Nikita Popov 2020-09-04 22:40:46 +02:00
parent 7a78068564
commit a8497a77ba
2 changed files with 16 additions and 8 deletions
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8
lib/Analysis/DemandedBits.cpp
View File

@ -170,6 +170,14 @@ void DemandedBits::determineLiveOperandBits(
} }
break; break;
} }
case Intrinsic::umax:
case Intrinsic::umin:
case Intrinsic::smax:
case Intrinsic::smin:
// If low bits of result are not demanded, they are also not demanded
// for the min/max operands.
AB = APInt::getBitsSetFrom(BitWidth, AOut.countTrailingZeros());
break;
} }
} }
break; break;

16
test/Transforms/BDCE/intrinsics.ll
View File

@ -8,8 +8,8 @@ declare i8 @llvm.smin.i8(i8, i8)
define i8 @umax(i8 %x, i8 %y, i1 %a, i1 %b) { define i8 @umax(i8 %x, i8 %y, i1 %a, i1 %b) {
; CHECK-LABEL: @umax( ; CHECK-LABEL: @umax(
; CHECK-NEXT: [[A2:%.*]] = zext i1 [[A:%.*]] to i8 ; CHECK-NEXT: [[A2:%.*]] = zext i1 false to i8
; CHECK-NEXT: [[B2:%.*]] = zext i1 [[B:%.*]] to i8 ; CHECK-NEXT: [[B2:%.*]] = zext i1 false to i8
; CHECK-NEXT: [[X2:%.*]] = or i8 [[X:%.*]], [[A2]] ; CHECK-NEXT: [[X2:%.*]] = or i8 [[X:%.*]], [[A2]]
; CHECK-NEXT: [[Y2:%.*]] = or i8 [[Y:%.*]], [[B2]] ; CHECK-NEXT: [[Y2:%.*]] = or i8 [[Y:%.*]], [[B2]]
; CHECK-NEXT: [[M:%.*]] = call i8 @llvm.umax.i8(i8 [[X2]], i8 [[Y2]]) ; CHECK-NEXT: [[M:%.*]] = call i8 @llvm.umax.i8(i8 [[X2]], i8 [[Y2]])
@ -27,8 +27,8 @@ define i8 @umax(i8 %x, i8 %y, i1 %a, i1 %b) {
define i8 @umin(i8 %x, i8 %y, i1 %a, i1 %b) { define i8 @umin(i8 %x, i8 %y, i1 %a, i1 %b) {
; CHECK-LABEL: @umin( ; CHECK-LABEL: @umin(
; CHECK-NEXT: [[A2:%.*]] = zext i1 [[A:%.*]] to i8 ; CHECK-NEXT: [[A2:%.*]] = zext i1 false to i8
; CHECK-NEXT: [[B2:%.*]] = zext i1 [[B:%.*]] to i8 ; CHECK-NEXT: [[B2:%.*]] = zext i1 false to i8
; CHECK-NEXT: [[X2:%.*]] = or i8 [[X:%.*]], [[A2]] ; CHECK-NEXT: [[X2:%.*]] = or i8 [[X:%.*]], [[A2]]
; CHECK-NEXT: [[Y2:%.*]] = or i8 [[Y:%.*]], [[B2]] ; CHECK-NEXT: [[Y2:%.*]] = or i8 [[Y:%.*]], [[B2]]
; CHECK-NEXT: [[M:%.*]] = call i8 @llvm.umin.i8(i8 [[X2]], i8 [[Y2]]) ; CHECK-NEXT: [[M:%.*]] = call i8 @llvm.umin.i8(i8 [[X2]], i8 [[Y2]])
@ -46,8 +46,8 @@ define i8 @umin(i8 %x, i8 %y, i1 %a, i1 %b) {
define i8 @smax(i8 %x, i8 %y, i1 %a, i1 %b) { define i8 @smax(i8 %x, i8 %y, i1 %a, i1 %b) {
; CHECK-LABEL: @smax( ; CHECK-LABEL: @smax(
; CHECK-NEXT: [[A2:%.*]] = zext i1 [[A:%.*]] to i8 ; CHECK-NEXT: [[A2:%.*]] = zext i1 false to i8
; CHECK-NEXT: [[B2:%.*]] = zext i1 [[B:%.*]] to i8 ; CHECK-NEXT: [[B2:%.*]] = zext i1 false to i8
; CHECK-NEXT: [[X2:%.*]] = or i8 [[X:%.*]], [[A2]] ; CHECK-NEXT: [[X2:%.*]] = or i8 [[X:%.*]], [[A2]]
; CHECK-NEXT: [[Y2:%.*]] = or i8 [[Y:%.*]], [[B2]] ; CHECK-NEXT: [[Y2:%.*]] = or i8 [[Y:%.*]], [[B2]]
; CHECK-NEXT: [[M:%.*]] = call i8 @llvm.smax.i8(i8 [[X2]], i8 [[Y2]]) ; CHECK-NEXT: [[M:%.*]] = call i8 @llvm.smax.i8(i8 [[X2]], i8 [[Y2]])
@ -65,8 +65,8 @@ define i8 @smax(i8 %x, i8 %y, i1 %a, i1 %b) {
define i8 @smin(i8 %x, i8 %y, i1 %a, i1 %b) { define i8 @smin(i8 %x, i8 %y, i1 %a, i1 %b) {
; CHECK-LABEL: @smin( ; CHECK-LABEL: @smin(
; CHECK-NEXT: [[A2:%.*]] = zext i1 [[A:%.*]] to i8 ; CHECK-NEXT: [[A2:%.*]] = zext i1 false to i8
; CHECK-NEXT: [[B2:%.*]] = zext i1 [[B:%.*]] to i8 ; CHECK-NEXT: [[B2:%.*]] = zext i1 false to i8
; CHECK-NEXT: [[X2:%.*]] = or i8 [[X:%.*]], [[A2]] ; CHECK-NEXT: [[X2:%.*]] = or i8 [[X:%.*]], [[A2]]
; CHECK-NEXT: [[Y2:%.*]] = or i8 [[Y:%.*]], [[B2]] ; CHECK-NEXT: [[Y2:%.*]] = or i8 [[Y:%.*]], [[B2]]
; CHECK-NEXT: [[M:%.*]] = call i8 @llvm.smin.i8(i8 [[X2]], i8 [[Y2]]) ; CHECK-NEXT: [[M:%.*]] = call i8 @llvm.smin.i8(i8 [[X2]], i8 [[Y2]])