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[InstCombine] cttz(abs(x)) -> cttz(x) 

Summary: Signedness does not change number of trailing zeros.

Reviewers: spatel, lebedev.ri, nikic

Reviewed By: lebedev.ri

Differential Revision: https://reviews.llvm.org/D63546

llvm-svn: 364064
This commit is contained in:
David Bolvansky 2019-06-21 15:26:22 +00:00
parent 000f25a37e
commit 4b28478389
2 changed files with 25 additions and 36 deletions
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19
llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
View File

@ -1194,10 +1194,21 @@ static Instruction *foldCttzCtlz(IntrinsicInst &II, InstCombiner &IC) {
return CallInst::Create(F, {X, II.getArgOperand(1)});
}
// cttz(-x) -> cttz(x)
if (IsTZ && match(Op0, m_Neg(m_Value(X)))) {
II.setOperand(0, X);
return ⅈ
if (IsTZ) {
// cttz(-x) -> cttz(x)
if (match(Op0, m_Neg(m_Value(X)))) {
II.setOperand(0, X);
return ⅈ
}
// cttz(abs(x)) -> cttz(x)
// cttz(nabs(x)) -> cttz(x)
Value *Y;
SelectPatternFlavor SPF = matchSelectPattern(Op0, X, Y).Flavor;
if (SPF == SPF_ABS || SPF == SPF_NABS) {
II.setOperand(0, X);
return ⅈ
}
}
KnownBits Known = IC.computeKnownBits(Op0, 0, &II);

42
llvm/test/Transforms/InstCombine/cttz-abs.ll
View File

@ -3,10 +3,7 @@
define i32 @cttz_abs(i32 %x) {
; CHECK-LABEL: @cttz_abs(
; CHECK-NEXT: [[C:%.*]] = icmp slt i32 [[X:%.*]], 0
; CHECK-NEXT: [[S:%.*]] = sub i32 0, [[X]]
; CHECK-NEXT: [[D:%.*]] = select i1 [[C]], i32 [[S]], i32 [[X]]
; CHECK-NEXT: [[R:%.*]] = tail call i32 @llvm.cttz.i32(i32 [[D]], i1 true), !range !0
; CHECK-NEXT: [[R:%.*]] = tail call i32 @llvm.cttz.i32(i32 [[X:%.*]], i1 true), !range !0
; CHECK-NEXT: ret i32 [[R]]
;
%c = icmp slt i32 %x, 0
@ -18,10 +15,7 @@ define i32 @cttz_abs(i32 %x) {
define <2 x i64> @cttz_abs_vec(<2 x i64> %x) {
; CHECK-LABEL: @cttz_abs_vec(
; CHECK-NEXT: [[C:%.*]] = icmp slt <2 x i64> [[X:%.*]], zeroinitializer
; CHECK-NEXT: [[S:%.*]] = sub <2 x i64> zeroinitializer, [[X]]
; CHECK-NEXT: [[D:%.*]] = select <2 x i1> [[C]], <2 x i64> [[S]], <2 x i64> [[X]]
; CHECK-NEXT: [[R:%.*]] = call <2 x i64> @llvm.cttz.v2i64(<2 x i64> [[D]], i1 false)
; CHECK-NEXT: [[R:%.*]] = call <2 x i64> @llvm.cttz.v2i64(<2 x i64> [[X:%.*]], i1 false)
; CHECK-NEXT: ret <2 x i64> [[R]]
;
%c = icmp slt <2 x i64> %x, zeroinitializer
@ -35,9 +29,7 @@ define i32 @cttz_abs2(i32 %x) {
; CHECK-LABEL: @cttz_abs2(
; CHECK-NEXT: [[C:%.*]] = icmp sgt i32 [[X:%.*]], 0
; CHECK-NEXT: call void @use_cond(i1 [[C]])
; CHECK-NEXT: [[S:%.*]] = sub i32 0, [[X]]
; CHECK-NEXT: [[D:%.*]] = select i1 [[C]], i32 [[X]], i32 [[S]]
; CHECK-NEXT: [[R:%.*]] = tail call i32 @llvm.cttz.i32(i32 [[D]], i1 true), !range !0
; CHECK-NEXT: [[R:%.*]] = tail call i32 @llvm.cttz.i32(i32 [[X]], i1 true), !range !0
; CHECK-NEXT: ret i32 [[R]]
;
%c = icmp sgt i32 %x, 0
@ -52,9 +44,7 @@ define i32 @cttz_abs3(i32 %x) {
; CHECK-LABEL: @cttz_abs3(
; CHECK-NEXT: [[C:%.*]] = icmp sgt i32 [[X:%.*]], -1
; CHECK-NEXT: call void @use_cond(i1 [[C]])
; CHECK-NEXT: [[S:%.*]] = sub i32 0, [[X]]
; CHECK-NEXT: [[D:%.*]] = select i1 [[C]], i32 [[X]], i32 [[S]]
; CHECK-NEXT: [[R:%.*]] = tail call i32 @llvm.cttz.i32(i32 [[D]], i1 true), !range !0
; CHECK-NEXT: [[R:%.*]] = tail call i32 @llvm.cttz.i32(i32 [[X]], i1 true), !range !0
; CHECK-NEXT: ret i32 [[R]]
;
%c = icmp sgt i32 %x, -1
@ -67,10 +57,7 @@ define i32 @cttz_abs3(i32 %x) {
define i32 @cttz_abs4(i32 %x) {
; CHECK-LABEL: @cttz_abs4(
; CHECK-NEXT: [[C:%.*]] = icmp slt i32 [[X:%.*]], 0
; CHECK-NEXT: [[S:%.*]] = sub i32 0, [[X]]
; CHECK-NEXT: [[D:%.*]] = select i1 [[C]], i32 [[S]], i32 [[X]]
; CHECK-NEXT: [[R:%.*]] = tail call i32 @llvm.cttz.i32(i32 [[D]], i1 true), !range !0
; CHECK-NEXT: [[R:%.*]] = tail call i32 @llvm.cttz.i32(i32 [[X:%.*]], i1 true), !range !0
; CHECK-NEXT: ret i32 [[R]]
;
%c = icmp slt i32 %x, 1
@ -82,10 +69,7 @@ define i32 @cttz_abs4(i32 %x) {
define i32 @cttz_nabs(i32 %x) {
; CHECK-LABEL: @cttz_nabs(
; CHECK-NEXT: [[C:%.*]] = icmp slt i32 [[X:%.*]], 0
; CHECK-NEXT: [[S:%.*]] = sub i32 0, [[X]]
; CHECK-NEXT: [[D:%.*]] = select i1 [[C]], i32 [[X]], i32 [[S]]
; CHECK-NEXT: [[R:%.*]] = tail call i32 @llvm.cttz.i32(i32 [[D]], i1 false), !range !0
; CHECK-NEXT: [[R:%.*]] = tail call i32 @llvm.cttz.i32(i32 [[X:%.*]], i1 false), !range !0
; CHECK-NEXT: ret i32 [[R]]
;
%c = icmp slt i32 %x, 0
@ -97,10 +81,7 @@ define i32 @cttz_nabs(i32 %x) {
define <2 x i64> @cttz_nabs_vec(<2 x i64> %x) {
; CHECK-LABEL: @cttz_nabs_vec(
; CHECK-NEXT: [[C:%.*]] = icmp slt <2 x i64> [[X:%.*]], zeroinitializer
; CHECK-NEXT: [[S:%.*]] = sub <2 x i64> zeroinitializer, [[X]]
; CHECK-NEXT: [[D:%.*]] = select <2 x i1> [[C]], <2 x i64> [[X]], <2 x i64> [[S]]
; CHECK-NEXT: [[R:%.*]] = call <2 x i64> @llvm.cttz.v2i64(<2 x i64> [[D]], i1 false)
; CHECK-NEXT: [[R:%.*]] = call <2 x i64> @llvm.cttz.v2i64(<2 x i64> [[X:%.*]], i1 false)
; CHECK-NEXT: ret <2 x i64> [[R]]
;
%c = icmp slt <2 x i64> %x, zeroinitializer
@ -112,10 +93,7 @@ define <2 x i64> @cttz_nabs_vec(<2 x i64> %x) {
define i64 @cttz_abs_64(i64 %x) {
; CHECK-LABEL: @cttz_abs_64(
; CHECK-NEXT: [[C:%.*]] = icmp slt i64 [[X:%.*]], 0
; CHECK-NEXT: [[S:%.*]] = sub i64 0, [[X]]
; CHECK-NEXT: [[D:%.*]] = select i1 [[C]], i64 [[S]], i64 [[X]]
; CHECK-NEXT: [[R:%.*]] = call i64 @llvm.cttz.i64(i64 [[D]], i1 false), !range !1
; CHECK-NEXT: [[R:%.*]] = call i64 @llvm.cttz.i64(i64 [[X:%.*]], i1 false), !range !1
; CHECK-NEXT: ret i64 [[R]]
;
%c = icmp slt i64 %x, 0
@ -131,7 +109,7 @@ define i32 @cttz_abs_multiuse(i32 %x) {
; CHECK-NEXT: [[S:%.*]] = sub i32 0, [[X]]
; CHECK-NEXT: [[D:%.*]] = select i1 [[C]], i32 [[S]], i32 [[X]]
; CHECK-NEXT: call void @use_abs(i32 [[D]])
; CHECK-NEXT: [[R:%.*]] = tail call i32 @llvm.cttz.i32(i32 [[D]], i1 true), !range !0
; CHECK-NEXT: [[R:%.*]] = tail call i32 @llvm.cttz.i32(i32 [[X]], i1 true), !range !0
; CHECK-NEXT: ret i32 [[R]]
;
%c = icmp slt i32 %x, 1
@ -148,7 +126,7 @@ define i32 @cttz_nabs_multiuse(i32 %x) {
; CHECK-NEXT: [[S:%.*]] = sub i32 0, [[X]]
; CHECK-NEXT: [[D:%.*]] = select i1 [[C]], i32 [[X]], i32 [[S]]
; CHECK-NEXT: call void @use_abs(i32 [[D]])
; CHECK-NEXT: [[R:%.*]] = tail call i32 @llvm.cttz.i32(i32 [[D]], i1 true), !range !0
; CHECK-NEXT: [[R:%.*]] = tail call i32 @llvm.cttz.i32(i32 [[X]], i1 true), !range !0
; CHECK-NEXT: ret i32 [[R]]
;
%c = icmp slt i32 %x, 1