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> -----Original Message----- > From: Tamar Christina <tamar.christ...@arm.com> > Sent: Friday, September 23, 2022 10:34 AM > To: gcc-patches@gcc.gnu.org > Cc: nd <n...@arm.com>; Richard Earnshaw <richard.earns...@arm.com>; > Marcus Shawcroft <marcus.shawcr...@arm.com>; Kyrylo Tkachov > <kyrylo.tkac...@arm.com>; Richard Sandiford > <richard.sandif...@arm.com> > Subject: [PATCH 3/4]AArch64 Add SVE2 implementation for pow2 bitmask > division > > Hi All, > > In plenty of image and video processing code it's common to modify pixel > values by a widening operation and then scale them back into range by > dividing by 255. > > This patch adds an named function to allow us to emit an optimized > sequence when doing an unsigned division that is equivalent to: > > x = y / (2 ^ (bitsize (y)/2)-1) > > For SVE2 this means we generate for: > > void draw_bitmap1(uint8_t* restrict pixel, uint8_t level, int n) { > for (int i = 0; i < (n & -16); i+=1) > pixel[i] = (pixel[i] * level) / 0xff; } > > the following: > > mov z3.b, #1 > .L3: > ld1b z0.h, p0/z, [x0, x3] > mul z0.h, p1/m, z0.h, z2.h > addhnb z1.b, z0.h, z3.h > addhnb z0.b, z0.h, z1.h > st1b z0.h, p0, [x0, x3] > inch x3 > whilelo p0.h, w3, w2 > b.any .L3 > > instead of: > > .L3: > ld1b z0.h, p1/z, [x0, x3] > mul z0.h, p0/m, z0.h, z1.h > umulh z0.h, p0/m, z0.h, z2.h > lsr z0.h, z0.h, #7 > st1b z0.h, p1, [x0, x3] > inch x3 > whilelo p1.h, w3, w2 > b.any .L3 > > Which results in significantly faster code. > > Bootstrapped Regtested on aarch64-none-linux-gnu and no issues. > > Ok for master? > > Thanks, > Tamar > > gcc/ChangeLog: > > * config/aarch64/aarch64-sve2.md > (@aarch64_bitmask_udiv<mode>3): New. > > gcc/testsuite/ChangeLog: > > * gcc.target/aarch64/sve2/div-by-bitmask_1.c: New test. > > --- inline copy of patch -- > diff --git a/gcc/config/aarch64/aarch64-sve2.md > b/gcc/config/aarch64/aarch64-sve2.md > index > f138f4be4bcf74c1a4a6d5847ed831435246737f..4d097f7c405cc68a1d6cda5c234 > a1023a6eba0d1 100644 > --- a/gcc/config/aarch64/aarch64-sve2.md > +++ b/gcc/config/aarch64/aarch64-sve2.md > @@ -71,6 +71,7 @@ > ;; ---- [INT] Reciprocal approximation > ;; ---- [INT<-FP] Base-2 logarithm > ;; ---- [INT] Polynomial multiplication > +;; ---- [INT] Misc optab implementations > ;; > ;; == Permutation > ;; ---- [INT,FP] General permutes > @@ -2312,6 +2313,47 @@ (define_insn "@aarch64_sve_<optab><mode>" > "<sve_int_op>\t%0.<Vewtype>, %1.<Vetype>, %2.<Vetype>" > ) > > +;; > +----------------------------------------------------------------------- > +-- ;; ---- [INT] Misc optab implementations ;; > +----------------------------------------------------------------------- > +-- > +;; Includes: > +;; - aarch64_bitmask_udiv > +;; > +----------------------------------------------------------------------- > +-- > + > +;; div optimizations using narrowings > +;; we can do the division e.g. shorts by 255 faster by calculating it > +as ;; (x + ((x + 257) >> 8)) >> 8 assuming the operation is done in ;; > +double the precision of x. > +;; > +;; See aarch64-simd.md for bigger explanation. > +(define_expand "@aarch64_bitmask_udiv<mode>3" > + [(match_operand:SVE_FULL_HSDI 0 "register_operand") > + (match_operand:SVE_FULL_HSDI 1 "register_operand") > + (match_operand:SVE_FULL_HSDI 2 "immediate_operand")] > + "TARGET_SVE2" > +{ > + unsigned HOST_WIDE_INT size > + = (1ULL << GET_MODE_UNIT_BITSIZE (<VNARROW>mode)) - 1; > + if (!CONST_VECTOR_P (operands[2]) > + || const_vector_encoded_nelts (operands[2]) != 1 > + || size != UINTVAL (CONST_VECTOR_ELT (operands[2], 0))) > + FAIL; > + > + rtx addend = gen_reg_rtx (<MODE>mode); > + rtx tmp1 = gen_reg_rtx (<VNARROW>mode); > + rtx tmp2 = gen_reg_rtx (<VNARROW>mode); > + rtx val = aarch64_simd_gen_const_vector_dup (<VNARROW>mode, 1); > + emit_move_insn (addend, lowpart_subreg (<MODE>mode, val, > +<VNARROW>mode)); > + emit_insn (gen_aarch64_sve (UNSPEC_ADDHNB, <MODE>mode, tmp1, > operands[1], > + addend)); > + emit_insn (gen_aarch64_sve (UNSPEC_ADDHNB, <MODE>mode, tmp2, > operands[1], > + lowpart_subreg (<MODE>mode, tmp1, > + <VNARROW>mode))); > + emit_move_insn (operands[0], > + lowpart_subreg (<MODE>mode, tmp2, > <VNARROW>mode)); > + DONE; > +}) > + > ;; > ========================================================== > =============== > ;; == Permutation > ;; > ========================================================== > =============== > diff --git a/gcc/testsuite/gcc.target/aarch64/sve2/div-by-bitmask_1.c > b/gcc/testsuite/gcc.target/aarch64/sve2/div-by-bitmask_1.c > new file mode 100644 > index > 0000000000000000000000000000000000000000..e6f5098c30f4e2eb8ed1af153c > 0bb0d204cda6d9 > --- /dev/null > +++ b/gcc/testsuite/gcc.target/aarch64/sve2/div-by-bitmask_1.c > @@ -0,0 +1,53 @@ > +/* { dg-do compile } */ > +/* { dg-additional-options "-O2 -std=c99" } */ > +/* { dg-final { check-function-bodies "**" "" "" { target { le } } } } > +*/ > + > +#include <stdint.h> > + > +/* > +** draw_bitmap1: > +** ... > +** mul z[0-9]+.h, p[0-9]+/m, z[0-9]+.h, z[0-9]+.h > +** addhnb z[0-9]+.b, z[0-9]+.h, z[0-9]+.h > +** addhnb z[0-9]+.b, z[0-9]+.h, z[0-9]+.h > +** ... > +*/ > +void draw_bitmap1(uint8_t* restrict pixel, uint8_t level, int n) { > + for (int i = 0; i < (n & -16); i+=1) > + pixel[i] = (pixel[i] * level) / 0xff; } > + > +void draw_bitmap2(uint8_t* restrict pixel, uint8_t level, int n) { > + for (int i = 0; i < (n & -16); i+=1) > + pixel[i] = (pixel[i] * level) / 0xfe; } > + > +/* > +** draw_bitmap3: > +** ... > +** mul z[0-9]+.s, p[0-9]+/m, z[0-9]+.s, z[0-9]+.s > +** addhnb z[0-9]+.h, z[0-9]+.s, z[0-9]+.s > +** addhnb z[0-9]+.h, z[0-9]+.s, z[0-9]+.s > +** ... > +*/ > +void draw_bitmap3(uint16_t* restrict pixel, uint16_t level, int n) { > + for (int i = 0; i < (n & -16); i+=1) > + pixel[i] = (pixel[i] * level) / 0xffffU; } > + > +/* > +** draw_bitmap4: > +** ... > +** mul z[0-9]+.d, p[0-9]+/m, z[0-9]+.d, z[0-9]+.d > +** addhnb z[0-9]+.s, z[0-9]+.d, z[0-9]+.d > +** addhnb z[0-9]+.s, z[0-9]+.d, z[0-9]+.d > +** ... > +*/ > +void draw_bitmap4(uint32_t* restrict pixel, uint32_t level, int n) { > + for (int i = 0; i < (n & -16); i+=1) > + pixel[i] = (pixel[i] * (uint64_t)level) / 0xffffffffUL; } > > > > > --