Failure after basepoints/gcc-13-4618-g17ae956c0fa: AArch64: Support new tbranch optab.:

Results changed to -10 # build_abe binutils: -9 # build_abe stage1: -5 # build_abe qemu: -2 # linux_n_obj: 7572 # First few build errors in logs: # 00:10:43 drivers/gpu/drm/v3d/v3d_perfmon.c:57:1: internal compiler error: in decompose, at rtl.h:2288 # 00:10:44 make[5]: *** [scripts/Makefile.build:250: drivers/gpu/drm/v3d/v3d_perfmon.o] Error 1 # 00:10:53 make[4]: *** [scripts/Makefile.build:502: drivers/gpu/drm/v3d] Error 2 # 00:13:52 drivers/media/mc/mc-device.c:198:1: internal compiler error: in decompose, at rtl.h:2288 # 00:13:53 make[4]: *** [scripts/Makefile.build:250: drivers/media/mc/mc-device.o] Error 1 # 00:13:57 make[3]: *** [scripts/Makefile.build:502: drivers/media/mc] Error 2 # 00:15:27 make[2]: *** [scripts/Makefile.build:502: drivers/media] Error 2 # 00:17:50 make[3]: *** [scripts/Makefile.build:502: drivers/gpu/drm] Error 2 # 00:17:50 make[2]: *** [scripts/Makefile.build:502: drivers/gpu] Error 2 # 00:17:50 make[1]: *** [scripts/Makefile.build:502: drivers] Error 2

from -10 # build_abe binutils: -9 # build_abe stage1: -5 # build_abe qemu: -2 # linux_n_obj: 8625 # linux build successful: all # linux boot successful: boot

THIS IS THE END OF INTERESTING STUFF. BELOW ARE LINKS TO BUILDS, REPRODUCTION INSTRUCTIONS, AND THE RAW COMMIT.

For latest status see comments in https://linaro.atlassian.net/browse/GNU-680 . Status of basepoints/gcc-13-4618-g17ae956c0fa commit for tcwg_kernel: commit 17ae956c0fa6baac3d22764019d5dd5ebf5c2b11 Author: Tamar Christina tamar.christina@arm.com Date: Mon Dec 12 15:18:56 2022 +0000

AArch64: Support new tbranch optab.

This implements the new tbranch optab for AArch64.

we cannot emit one big RTL for the final instruction immediately. The reason that all comparisons in the AArch64 backend expand to separate CC compares, and separate testing of the operands is for ifcvt.

The separate CC compare is needed so ifcvt can produce csel, cset etc from the compares. Unlike say combine, ifcvt can not do recog on a parallel with a clobber. Should we emit the instruction directly then ifcvt will not be able to say, make a csel, because we have no patterns which handle zero_extract and compare. (unlike combine ifcvt cannot transform the extract into an AND).

While you could provide various patterns for this (and I did try) you end up with broken patterns because you can't add the clobber to the CC register. If you do, ifcvt recog fails.

i.e.

int f1 (int x) { if (x & 1) return 1; return x; }

We lose csel here.

Secondly the reason the compare with an explicit CC mode is needed is so that ifcvt can transform the operation into a version that doesn't require the flags to be set. But it only does so if it know the explicit usage of the CC reg.

For instance

int foo (int a, int b) { return ((a & (1 << 25)) ? 5 : 4); }

Doesn't require a comparison, the optimal form is:

foo(int, int): ubfx x0, x0, 25, 1 add w0, w0, 4 ret

and no compare is actually needed. If you represent the instruction using an ANDS instead of a zero_extract then you get close, but you end up with an ands followed by an add, which is a slower operation.

gcc/ChangeLog:

* config/aarch64/aarch64.md (*tb<optab><mode>1): Rename to... (*tb<optab>ALLI:modeGPI:mode1): ... this. (tbranch_<code><mode>4): New. * config/aarch64/iterators.md(ZEROM, zerom): New.

gcc/testsuite/ChangeLog:

* gcc.target/aarch64/tbz_1.c: New test. * gnu-master-aarch64-mainline-defconfig ** Failure after basepoints/gcc-13-4618-g17ae956c0fa: AArch64: Support new tbranch optab.: ** https://ci.linaro.org/job/tcwg_kernel-gnu-build-gnu-master-aarch64-mainline-...

Bad build: https://ci.linaro.org/job/tcwg_kernel-gnu-build-gnu-master-aarch64-mainline-... Good build: https://ci.linaro.org/job/tcwg_kernel-gnu-build-gnu-master-aarch64-mainline-...

Reproduce current build: <cut> mkdir -p investigate-gcc-17ae956c0fa6baac3d22764019d5dd5ebf5c2b11 cd investigate-gcc-17ae956c0fa6baac3d22764019d5dd5ebf5c2b11

# Fetch scripts git clone https://git.linaro.org/toolchain/jenkins-scripts

# Fetch manifests for bad and good builds mkdir -p bad/artifacts good/artifacts curl -o bad/artifacts/manifest.sh https://ci.linaro.org/job/tcwg_kernel-gnu-build-gnu-master-aarch64-mainline-... --fail curl -o good/artifacts/manifest.sh https://ci.linaro.org/job/tcwg_kernel-gnu-build-gnu-master-aarch64-mainline-... --fail

# Reproduce bad build (cd bad; ../jenkins-scripts/tcwg_kernel-build.sh ^^ true %%rr[top_artifacts] artifacts) # Reproduce good build (cd good; ../jenkins-scripts/tcwg_kernel-build.sh ^^ true %%rr[top_artifacts] artifacts) </cut>

Full commit (up to 1000 lines): <cut> commit 17ae956c0fa6baac3d22764019d5dd5ebf5c2b11 Author: Tamar Christina tamar.christina@arm.com Date: Mon Dec 12 15:18:56 2022 +0000

AArch64: Support new tbranch optab.

This implements the new tbranch optab for AArch64.

we cannot emit one big RTL for the final instruction immediately. The reason that all comparisons in the AArch64 backend expand to separate CC compares, and separate testing of the operands is for ifcvt.

The separate CC compare is needed so ifcvt can produce csel, cset etc from the compares. Unlike say combine, ifcvt can not do recog on a parallel with a clobber. Should we emit the instruction directly then ifcvt will not be able to say, make a csel, because we have no patterns which handle zero_extract and compare. (unlike combine ifcvt cannot transform the extract into an AND).

While you could provide various patterns for this (and I did try) you end up with broken patterns because you can't add the clobber to the CC register. If you do, ifcvt recog fails.

i.e.

int f1 (int x) { if (x & 1) return 1; return x; }

We lose csel here.

Secondly the reason the compare with an explicit CC mode is needed is so that ifcvt can transform the operation into a version that doesn't require the flags to be set. But it only does so if it know the explicit usage of the CC reg.

For instance

int foo (int a, int b) { return ((a & (1 << 25)) ? 5 : 4); }

Doesn't require a comparison, the optimal form is:

foo(int, int): ubfx x0, x0, 25, 1 add w0, w0, 4 ret

and no compare is actually needed. If you represent the instruction using an ANDS instead of a zero_extract then you get close, but you end up with an ands followed by an add, which is a slower operation.

gcc/ChangeLog:

* config/aarch64/aarch64.md (*tb<optab><mode>1): Rename to... (*tb<optab>ALLI:modeGPI:mode1): ... this. (tbranch_<code><mode>4): New. * config/aarch64/iterators.md(ZEROM, zerom): New.

gcc/testsuite/ChangeLog:

* gcc.target/aarch64/tbz_1.c: New test. --- gcc/config/aarch64/aarch64.md | 33 ++++++++--- gcc/config/aarch64/iterators.md | 2 + gcc/testsuite/gcc.target/aarch64/tbz_1.c | 95 ++++++++++++++++++++++++++++++++ 3 files changed, 122 insertions(+), 8 deletions(-)

diff --git a/gcc/config/aarch64/aarch64.md b/gcc/config/aarch64/aarch64.md index 896b6a8ac79..d749c98eef6 100644 --- a/gcc/config/aarch64/aarch64.md +++ b/gcc/config/aarch64/aarch64.md @@ -947,12 +947,29 @@ (const_int 1)))] )

-(define_insn "*tb<optab><mode>1" +(define_expand "tbranch_<code><mode>3" [(set (pc) (if_then_else - (EQL (zero_extract:DI (match_operand:GPI 0 "register_operand" "r") - (const_int 1) - (match_operand 1 - "aarch64_simd_shift_imm_<mode>" "n")) + (EQL (match_operand:ALLI 0 "register_operand") + (match_operand 1 "aarch64_simd_shift_imm_<mode>")) + (label_ref (match_operand 2 "")) + (pc)))] + "" +{ + rtx bitvalue = gen_reg_rtx (<ZEROM>mode); + rtx reg = gen_lowpart (<ZEROM>mode, operands[0]); + rtx val = GEN_INT (1UL << UINTVAL (operands[1])); + emit_insn (gen_and<zerom>3 (bitvalue, reg, val)); + operands[1] = const0_rtx; + operands[0] = aarch64_gen_compare_reg (<CODE>, bitvalue, + operands[1]); +}) + +(define_insn "*tb<optab>ALLI:modeGPI:mode1" + [(set (pc) (if_then_else + (EQL (zero_extract:GPI (match_operand:ALLI 0 "register_operand" "r") + (const_int 1) + (match_operand 1 + "aarch64_simd_shift_imm_ALLI:mode" "n")) (const_int 0)) (label_ref (match_operand 2 "" "")) (pc))) @@ -963,15 +980,15 @@ { if (get_attr_far_branch (insn) == 1) return aarch64_gen_far_branch (operands, 2, "Ltb", - "<inv_tb>\t%<w>0, %1, "); + "<inv_tb>\t%ALLI:w0, %1, "); else { operands[1] = GEN_INT (HOST_WIDE_INT_1U << UINTVAL (operands[1])); - return "tst\t%<w>0, %1;<bcond>\t%l2"; + return "tst\t%ALLI:w0, %1;<bcond>\t%l2"; } } else - return "<tbz>\t%<w>0, %1, %l2"; + return "<tbz>\t%ALLI:w0, %1, %l2"; } [(set_attr "type" "branch") (set (attr "length") diff --git a/gcc/config/aarch64/iterators.md b/gcc/config/aarch64/iterators.md index d10cf93572e..a521dbde1ec 100644 --- a/gcc/config/aarch64/iterators.md +++ b/gcc/config/aarch64/iterators.md @@ -1107,6 +1107,8 @@

;; Give the number of bits in the mode (define_mode_attr sizen [(QI "8") (HI "16") (SI "32") (DI "64")]) +(define_mode_attr ZEROM [(QI "SI") (HI "SI") (SI "SI") (DI "DI")]) +(define_mode_attr zerom [(QI "si") (HI "si") (SI "si") (DI "di")])

;; Give the ordinal of the MSB in the mode (define_mode_attr sizem1 [(QI "#7") (HI "#15") (SI "#31") (DI "#63") diff --git a/gcc/testsuite/gcc.target/aarch64/tbz_1.c b/gcc/testsuite/gcc.target/aarch64/tbz_1.c new file mode 100644 index 00000000000..39deb58e278 --- /dev/null +++ b/gcc/testsuite/gcc.target/aarch64/tbz_1.c @@ -0,0 +1,95 @@ +/* { dg-do compile } */ +/* { dg-additional-options "-O2 -std=c99 -fno-unwind-tables -fno-asynchronous-unwind-tables" } */ +/* { dg-final { check-function-bodies "**" "" "" { target { le } } } } */ + +#include <stdbool.h> + +void h(void); + +/* +** g1: +** tbnz w[0-9]+, #?0, .L([0-9]+) +** ret +** ... +*/ +void g1(bool x) +{ + if (__builtin_expect (x, 0)) + h (); +} + +/* +** g2: +** tbz w[0-9]+, #?0, .L([0-9]+) +** b h +** ... +*/ +void g2(bool x) +{ + if (__builtin_expect (x, 1)) + h (); +} + +/* +** g3_ge: +** tbnz w[0-9]+, #?31, .L[0-9]+ +** b h +** ... +*/ +void g3_ge(int x) +{ + if (__builtin_expect (x >= 0, 1)) + h (); +} + +/* +** g3_gt: +** cmp w[0-9]+, 0 +** ble .L[0-9]+ +** b h +** ... +*/ +void g3_gt(int x) +{ + if (__builtin_expect (x > 0, 1)) + h (); +} + +/* +** g3_lt: +** tbz w[0-9]+, #?31, .L[0-9]+ +** b h +** ... +*/ +void g3_lt(int x) +{ + if (__builtin_expect (x < 0, 1)) + h (); +} + +/* +** g3_le: +** cmp w[0-9]+, 0 +** bgt .L[0-9]+ +** b h +** ... +*/ +void g3_le(int x) +{ + if (__builtin_expect (x <= 0, 1)) + h (); +} + +/* +** g5: +** mov w[0-9]+, 65279 +** tst w[0-9]+, w[0-9]+ +** beq .L[0-9]+ +** b h +** ... +*/ +void g5(int x) +{ + if (__builtin_expect (x & 0xfeff, 1)) + h (); +} </cut>