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Differential D154677

[InstCombine] Add tests for folding `fmul`/`fdiv` by Pow2 to `add`/`sub` of exp; NFC
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Authored by goldstein.w.n on Jul 6 2023, 8:25 PM.

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Reviewers
nikic
RKSimon
arsenm

Diff Detail

Unit TestsFailed

TimeTest
60,070 msx64 debian > ThreadSanitizer-x86_64.ThreadSanitizer-x86_64::restore_stack.cpp

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goldstein.w.n created this revision.Jul 6 2023, 8:25 PM
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goldstein.w.n added a child revision: D154678: [InstCombine] Fold IEEE `fmul`/`fdiv` by Pow2 to `add`/`sub` of exp.Jul 6 2023, 8:26 PM
Harbormaster completed remote builds in B243645: Diff 537967.Jul 6 2023, 9:51 PM
arsenm added inline comments.Jul 7 2023, 3:57 AM
llvm/test/Transforms/InstCombine/fmul-and-fdiv-by-int-pow2.ll
14

Add some tests that show flag preservation on fmul/fdiv

182

Are the nuws relevant?

goldstein.w.n added inline comments.Jul 7 2023, 8:31 AM
llvm/test/Transforms/InstCombine/fmul-and-fdiv-by-int-pow2.ll
14

Hmm? Can you link to example or reference?

182

They get added anyways for (shl 1, cnt). They are used to make non-zero status easy to determine.

Revision Contents

PathSize
llvm/
test/
Transforms/
InstCombine/
214 lines

Diff 537967

llvm/test/Transforms/InstCombine/fmul-and-fdiv-by-int-pow2.ll

  • This file was added.
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 3
; RUN: opt < %s -passes=instcombine -S | FileCheck %s
define double @fmul_dbl_pow_1_shl_cnt(i64 %cnt) {
; CHECK-LABEL: define double @fmul_dbl_pow_1_shl_cnt
; CHECK-SAME: (i64 [[CNT:%.*]]) {
; CHECK-NEXT: [[SHL:%.*]] = shl nuw i64 1, [[CNT]]
; CHECK-NEXT: [[CONV:%.*]] = uitofp i64 [[SHL]] to double
; CHECK-NEXT: [[MUL:%.*]] = fmul double [[CONV]], 9.000000e+00
; CHECK-NEXT: ret double [[MUL]]
;
%shl = shl nuw i64 1, %cnt
%conv = uitofp i64 %shl to double
%mul = fmul double 9.000000e+00, %conv
arsenmUnsubmitted
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Add some tests that show flag preservation on fmul/fdiv

arsenm: Add some tests that show flag preservation on fmul/fdiv
goldstein.w.nAuthorUnsubmitted
Done
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Hmm? Can you link to example or reference?

goldstein.w.n: Hmm? Can you link to example or reference?
ret double %mul
}
define double @fmul_dbl_pow_1_shl_cnt_fail_maybe_non_pow2(i64 %v, i64 %cnt) {
; CHECK-LABEL: define double @fmul_dbl_pow_1_shl_cnt_fail_maybe_non_pow2
; CHECK-SAME: (i64 [[V:%.*]], i64 [[CNT:%.*]]) {
; CHECK-NEXT: [[SHL:%.*]] = shl nuw i64 [[V]], [[CNT]]
; CHECK-NEXT: [[CONV:%.*]] = uitofp i64 [[SHL]] to double
; CHECK-NEXT: [[MUL:%.*]] = fmul double [[CONV]], 9.000000e+00
; CHECK-NEXT: ret double [[MUL]]
;
%shl = shl nuw i64 %v, %cnt
%conv = uitofp i64 %shl to double
%mul = fmul double 9.000000e+00, %conv
ret double %mul
}
define float @fmul_pow_1_shl_cnt(i64 %cnt) {
; CHECK-LABEL: define float @fmul_pow_1_shl_cnt
; CHECK-SAME: (i64 [[CNT:%.*]]) {
; CHECK-NEXT: [[SHL:%.*]] = shl nuw nsw i64 8, [[CNT]]
; CHECK-NEXT: [[CONV:%.*]] = uitofp i64 [[SHL]] to float
; CHECK-NEXT: [[MUL:%.*]] = fmul float [[CONV]], -9.000000e+00
; CHECK-NEXT: ret float [[MUL]]
;
%shl = shl nsw nuw i64 8, %cnt
%conv = uitofp i64 %shl to float
%mul = fmul float -9.000000e+00, %conv
ret float %mul
}
define <2 x float> @fmul_pow_2_shl_cnt_vec(<2 x i64> %cnt) {
; CHECK-LABEL: define <2 x float> @fmul_pow_2_shl_cnt_vec
; CHECK-SAME: (<2 x i64> [[CNT:%.*]]) {
; CHECK-NEXT: [[SHL:%.*]] = shl nuw nsw <2 x i64> <i64 2, i64 2>, [[CNT]]
; CHECK-NEXT: [[CONV:%.*]] = uitofp <2 x i64> [[SHL]] to <2 x float>
; CHECK-NEXT: [[MUL:%.*]] = fmul <2 x float> [[CONV]], <float 1.500000e+01, float 1.500000e+01>
; CHECK-NEXT: ret <2 x float> [[MUL]]
;
%shl = shl nsw nuw <2 x i64> <i64 2, i64 2>, %cnt
%conv = uitofp <2 x i64> %shl to <2 x float>
%mul = fmul <2 x float> <float 15.000000e+00, float 15.000000e+00>, %conv
ret <2 x float> %mul
}
define <2 x half> @fmul_pow_2_shl_cnt_vec_to_large(<2 x i64> %cnt) {
; CHECK-LABEL: define <2 x half> @fmul_pow_2_shl_cnt_vec_to_large
; CHECK-SAME: (<2 x i64> [[CNT:%.*]]) {
; CHECK-NEXT: [[SHL:%.*]] = shl nuw nsw <2 x i64> <i64 2, i64 2>, [[CNT]]
; CHECK-NEXT: [[CONV:%.*]] = uitofp <2 x i64> [[SHL]] to <2 x half>
; CHECK-NEXT: [[MUL:%.*]] = fmul <2 x half> [[CONV]], <half 0xH4B80, half 0xH4B80>
; CHECK-NEXT: ret <2 x half> [[MUL]]
;
%shl = shl nsw nuw <2 x i64> <i64 2, i64 2>, %cnt
%conv = uitofp <2 x i64> %shl to <2 x half>
%mul = fmul <2 x half> <half 15.000000e+00, half 15.000000e+00>, %conv
ret <2 x half> %mul
}
define double @fmul_pow_1_shl_cnt_fail_maybe_bad_exp(i64 %cnt) {
; CHECK-LABEL: define double @fmul_pow_1_shl_cnt_fail_maybe_bad_exp
; CHECK-SAME: (i64 [[CNT:%.*]]) {
; CHECK-NEXT: [[SHL:%.*]] = shl nuw i64 1, [[CNT]]
; CHECK-NEXT: [[CONV:%.*]] = uitofp i64 [[SHL]] to double
; CHECK-NEXT: [[MUL:%.*]] = fmul double [[CONV]], 0x7BEFFFFFFF5F3992
; CHECK-NEXT: ret double [[MUL]]
;
%shl = shl nuw i64 1, %cnt
%conv = uitofp i64 %shl to double
%mul = fmul double 9.745314e+288, %conv
ret double %mul
}
define double @fmul_pow_1_shl_cnt_safe(i16 %cnt) {
; CHECK-LABEL: define double @fmul_pow_1_shl_cnt_safe
; CHECK-SAME: (i16 [[CNT:%.*]]) {
; CHECK-NEXT: [[SHL:%.*]] = shl nuw i16 1, [[CNT]]
; CHECK-NEXT: [[CONV:%.*]] = uitofp i16 [[SHL]] to double
; CHECK-NEXT: [[MUL:%.*]] = fmul double [[CONV]], 0x7BEFFFFFFF5F3992
; CHECK-NEXT: ret double [[MUL]]
;
%shl = shl nuw i16 1, %cnt
%conv = uitofp i16 %shl to double
%mul = fmul double 9.745314e+288, %conv
ret double %mul
}
define <2 x double> @fdiv_pow_1_shl_cnt_vec(<2 x i64> %cnt) {
; CHECK-LABEL: define <2 x double> @fdiv_pow_1_shl_cnt_vec
; CHECK-SAME: (<2 x i64> [[CNT:%.*]]) {
; CHECK-NEXT: [[SHL:%.*]] = shl nuw <2 x i64> <i64 1, i64 1>, [[CNT]]
; CHECK-NEXT: [[CONV:%.*]] = uitofp <2 x i64> [[SHL]] to <2 x double>
; CHECK-NEXT: [[MUL:%.*]] = fdiv <2 x double> <double 1.000000e+00, double 1.000000e+00>, [[CONV]]
; CHECK-NEXT: ret <2 x double> [[MUL]]
;
%shl = shl nuw <2 x i64> <i64 1, i64 1>, %cnt
%conv = uitofp <2 x i64> %shl to <2 x double>
%mul = fdiv <2 x double> <double 1.000000e+00, double 1.000000e+00>, %conv
ret <2 x double> %mul
}
define float @fdiv_pow_1_shl_cnt_fail_maybe_z(i64 %cnt) {
; CHECK-LABEL: define float @fdiv_pow_1_shl_cnt_fail_maybe_z
; CHECK-SAME: (i64 [[CNT:%.*]]) {
; CHECK-NEXT: [[SHL:%.*]] = shl i64 8, [[CNT]]
; CHECK-NEXT: [[CONV:%.*]] = uitofp i64 [[SHL]] to float
; CHECK-NEXT: [[MUL:%.*]] = fdiv float -9.000000e+00, [[CONV]]
; CHECK-NEXT: ret float [[MUL]]
;
%shl = shl i64 8, %cnt
%conv = uitofp i64 %shl to float
%mul = fdiv float -9.000000e+00, %conv
ret float %mul
}
define float @fdiv_pow_1_shl_cnt_fail_neg_int(i64 %cnt) {
; CHECK-LABEL: define float @fdiv_pow_1_shl_cnt_fail_neg_int
; CHECK-SAME: (i64 [[CNT:%.*]]) {
; CHECK-NEXT: [[SHL:%.*]] = shl i64 8, [[CNT]]
; CHECK-NEXT: [[CONV:%.*]] = sitofp i64 [[SHL]] to float
; CHECK-NEXT: [[MUL:%.*]] = fdiv float -9.000000e+00, [[CONV]]
; CHECK-NEXT: ret float [[MUL]]
;
%shl = shl i64 8, %cnt
%conv = sitofp i64 %shl to float
%mul = fdiv float -9.000000e+00, %conv
ret float %mul
}
define float @fdiv_pow_1_shl_cnt(i64 %cnt_in) {
; CHECK-LABEL: define float @fdiv_pow_1_shl_cnt
; CHECK-SAME: (i64 [[CNT_IN:%.*]]) {
; CHECK-NEXT: [[CNT:%.*]] = and i64 [[CNT_IN]], 31
; CHECK-NEXT: [[SHL:%.*]] = shl i64 8, [[CNT]]
; CHECK-NEXT: [[CONV:%.*]] = sitofp i64 [[SHL]] to float
; CHECK-NEXT: [[MUL:%.*]] = fdiv float -5.000000e-01, [[CONV]]
; CHECK-NEXT: ret float [[MUL]]
;
%cnt = and i64 %cnt_in, 31
%shl = shl i64 8, %cnt
%conv = sitofp i64 %shl to float
%mul = fdiv float -0.500000e+00, %conv
ret float %mul
}
define half @fdiv_pow_1_shl_cnt_fail_out_of_bounds(i32 %cnt) {
; CHECK-LABEL: define half @fdiv_pow_1_shl_cnt_fail_out_of_bounds
; CHECK-SAME: (i32 [[CNT:%.*]]) {
; CHECK-NEXT: [[SHL:%.*]] = shl nuw i32 1, [[CNT]]
; CHECK-NEXT: [[CONV:%.*]] = uitofp i32 [[SHL]] to half
; CHECK-NEXT: [[MUL:%.*]] = fdiv half 0xH7000, [[CONV]]
; CHECK-NEXT: ret half [[MUL]]
;
%shl = shl nuw i32 1, %cnt
%conv = uitofp i32 %shl to half
%mul = fdiv half 0xH7000, %conv
ret half %mul
}
define half @fdiv_pow_1_shl_cnt_in_bounds(i16 %cnt) {
; CHECK-LABEL: define half @fdiv_pow_1_shl_cnt_in_bounds
; CHECK-SAME: (i16 [[CNT:%.*]]) {
; CHECK-NEXT: [[SHL:%.*]] = shl nuw i16 1, [[CNT]]
; CHECK-NEXT: [[CONV:%.*]] = uitofp i16 [[SHL]] to half
; CHECK-NEXT: [[MUL:%.*]] = fdiv half 0xH7000, [[CONV]]
; CHECK-NEXT: ret half [[MUL]]
;
%shl = shl nuw i16 1, %cnt
arsenmUnsubmitted
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Are the nuws relevant?

arsenm: Are the nuws relevant?
goldstein.w.nAuthorUnsubmitted
Done
ReplyInline Actions

They get added anyways for (shl 1, cnt). They are used to make non-zero status easy to determine.

goldstein.w.n: They get added anyways for `(shl 1, cnt)`. They are used to make non-zero status easy to…
%conv = uitofp i16 %shl to half
%mul = fdiv half 0xH7000, %conv
ret half %mul
}
define half @fdiv_pow_1_shl_cnt_in_bounds2(i16 %cnt) {
; CHECK-LABEL: define half @fdiv_pow_1_shl_cnt_in_bounds2
; CHECK-SAME: (i16 [[CNT:%.*]]) {
; CHECK-NEXT: [[SHL:%.*]] = shl nuw i16 1, [[CNT]]
; CHECK-NEXT: [[CONV:%.*]] = uitofp i16 [[SHL]] to half
; CHECK-NEXT: [[MUL:%.*]] = fdiv half 0xH4800, [[CONV]]
; CHECK-NEXT: ret half [[MUL]]
;
%shl = shl nuw i16 1, %cnt
%conv = uitofp i16 %shl to half
%mul = fdiv half 0xH4800, %conv
ret half %mul
}
define half @fdiv_pow_1_shl_cnt_in_bounds3(i16 %cnt) {
; CHECK-LABEL: define half @fdiv_pow_1_shl_cnt_in_bounds3
; CHECK-SAME: (i16 [[CNT:%.*]]) {
; CHECK-NEXT: [[SHL:%.*]] = shl nuw i16 1, [[CNT]]
; CHECK-NEXT: [[CONV:%.*]] = uitofp i16 [[SHL]] to half
; CHECK-NEXT: [[MUL:%.*]] = fdiv half 0xH3800, [[CONV]]
; CHECK-NEXT: ret half [[MUL]]
;
%shl = shl nuw i16 1, %cnt
%conv = uitofp i16 %shl to half
%mul = fdiv half 0xH3800, %conv
ret half %mul
}