[{"id":3685459,"web_url":"http://patchwork.ozlabs.org/comment/3685459/","msgid":"","list_archive_url":null,"date":"2026-05-03T22:18:11","subject":"Re: [PATCH] match: Optimize `A > B ? ABS(A) : B` to `MAX(A, B)` when\n B >= 0 [PR116700]","submitter":{"id":91428,"url":"http://patchwork.ozlabs.org/api/people/91428/","name":"Andrew Pinski","email":"andrew.pinski@oss.qualcomm.com"},"content":"On Sat, May 2, 2026 at 11:02 AM Avinal Kumar wrote:\n>\n> When B is known to be non-negative and A > B, A must be positive,\n> so ABS(A) == A. The whole expression (A > B ? ABS(A) : B) then\n> simplifies to MAX(A, B). This is caught at -O2 via VRP, but at\n> -O1 phiopt1 produces ABS_EXPR and no later pass simplifies it.\n>\n> PR tree-optimization/116700\n>\n> gcc/ChangeLog:\n>\n> * match.pd: (A > B ? ABS(A) : B -> MAX(A, B)): New pattern\n> for non-negative B.\n>\n> gcc/testsuite/ChangeLog:\n>\n> * gcc.dg/pr116700.c: New test.\n> * gcc.dg/tree-ssa/phi-opt-48.c: New test.\n>\n> Signed-off-by: Avinal Kumar \n> ---\n> I compared the changes in the suggested patch on bugzilla, understood patterns\n> and tried to adapt them. The actual mechanism is still not completely understood\n> to me. The tests are running fine but I think I am missing some cases.\n\nLet me go over the pattern with you (This could be used for future\npart of the tutorials):\n(for cmp (gt ge)\n// this is a for loop which says cmp will either be gt (GT_EXPR,\ngreater than expression) or ge (GE_EXPR, greater than or equal\nexpression).\n (simplify\n// (simplify a b) means simplify the matching a into b\n (cond (cmp:c @0 tree_expr_nonnegative_p@1) (abs @0) @1)\n// cond here is matching COND_EXPR which is a 3 operand expressions\nwhich is similar to the C operator `?:`.\n// cmp:c means match cmp and `:c` here means to handle commutative\nexpressions in swapping the lhs and rhs operands of the expressions.\n// But since this is a comparison, it means handling of the swapping\nof the operands and use the corresponding comparison.\n// That is `@0 < @1` and `@1 > @0` will match.\n// @0/@1 are captures\n// tree_expr_nonnegative_p is a predicate and returns true if the\nvalue is nonnegative. (there are many more predicates)\n// abs is short for ABS_EXPR which similar to the C function abs but\nis a tree expression rather than a function call (matching\nbuiltin/internal functions are supported too but we don't use them in\nthis case).\n (if (INTEGRAL_TYPE_P (type))\n// This says if the resulting type (type) is a scalar integral type (a\nboolean, integer, bitint or an enum type)\n (max @0 @1))))\n// This is the resulting expression in this case it is max.\n\n>\n> Here is how I ran the tests:\n>\n> make -j$(nproc)\n> make check-gcc RUNTESTFLAGS=\"tree-ssa.exp=phi-opt-48.c\"\n> make check-gcc RUNTESTFLAGS=\"dg.exp=pr116700.c\"\n>\n> On a side note, is there any trick/tips for building faster? I have a decent\n> system (8C 16T and 64GB RAM) and it takes almost an hour.\n\nYou can use one of the machines in the compile farm,\nhttps://gcc.gnu.org/wiki/CompileFarm.\nI will note you only ran a few testcases and not the full testsuite.\n\nThis patch is ok, I will push it after a full bootstrap test but next\ntime you should run the full testsuite.\n\nThanks,\nAndrew\n\n>\n> gcc/match.pd | 9 ++++++++\n> gcc/testsuite/gcc.dg/pr116700.c | 13 +++++++++++\n> gcc/testsuite/gcc.dg/tree-ssa/phi-opt-48.c | 25 ++++++++++++++++++++++\n> 3 files changed, 47 insertions(+)\n> create mode 100644 gcc/testsuite/gcc.dg/pr116700.c\n> create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/phi-opt-48.c\n>\n> diff --git a/gcc/match.pd b/gcc/match.pd\n> index dd9efb82c59..928f75c5a44 100644\n> --- a/gcc/match.pd\n> +++ b/gcc/match.pd\n> @@ -7276,6 +7276,15 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)\n> (if (INTEGRAL_TYPE_P (type))\n> @3))\n>\n> +/* A > B ? ABS(A) : B -> MAX(A, B) when B is non-negative.\n> + When A > B >= 0, A is positive so ABS(A) = A = MAX(A, B).\n> + When A <= B, the result is B = MAX(A, B). */\n> +(for cmp (gt ge)\n> + (simplify\n> + (cond (cmp:c @0 tree_expr_nonnegative_p@1) (abs @0) @1)\n> + (if (INTEGRAL_TYPE_P (type))\n> + (max @0 @1))))\n> +\n> /* (X + 1) > Y ? -X : 1 simplifies to X >= Y ? -X : 1 when\n> X is unsigned, as when X + 1 overflows, X is -1, so -X == 1. */\n> (simplify\n> diff --git a/gcc/testsuite/gcc.dg/pr116700.c b/gcc/testsuite/gcc.dg/pr116700.c\n> new file mode 100644\n> index 00000000000..a52388249a3\n> --- /dev/null\n> +++ b/gcc/testsuite/gcc.dg/pr116700.c\n> @@ -0,0 +1,13 @@\n> +/* PR tree-optimization/116700 */\n> +/* { dg-do compile } */\n> +/* { dg-options \"-O1 -fdump-tree-phiopt1\" } */\n> +\n> +int f(unsigned char a, int b, int c)\n> +{\n> + int t = a;\n> + if (c > t) t = (c > 0 ? c : -c);\n> + return t;\n> +}\n> +\n> +/* { dg-final { scan-tree-dump \"MAX_EXPR\" \"phiopt1\" } } */\n> +/* { dg-final { scan-tree-dump-not \"ABS_EXPR\" \"phiopt1\" } } */\n> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-48.c b/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-48.c\n> new file mode 100644\n> index 00000000000..06317766457\n> --- /dev/null\n> +++ b/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-48.c\n> @@ -0,0 +1,25 @@\n> +/* { dg-do compile } */\n> +/* { dg-options \"-O1 -fdump-tree-phiopt1\" } */\n> +\n> +/* Test that (A > B) ? ABS(A) : B is simplified to MAX(A, B)\n> + when B is known to be non-negative. */\n> +\n> +int f(unsigned char a, int b, int c)\n> +{\n> + int t = a;\n> + if (c > t)\n> + t = (c > 0 ? c : -c);\n> + return t;\n> +}\n> +\n> +int f1(unsigned char a, int b, int c)\n> +{\n> + int t = a;\n> + if (c > t) return (c > 0 ? c : -c);\n> + return t;\n> +}\n> +\n> +/* Both functions should be converted to MAX_EXPR by phiopt1. */\n> +/* { dg-final { scan-tree-dump-times \"MAX_EXPR\" 2 \"phiopt1\" } } */\n> +/* { dg-final { scan-tree-dump-not \"ABS_EXPR\" \"phiopt1\" } } */\n> +/* { dg-final { scan-tree-dump-not \"if \" \"phiopt1\" } } */\n> --\n> 2.54.0\n>","headers":{"Return-Path":"","X-Original-To":["incoming@patchwork.ozlabs.org","gcc-patches@gcc.gnu.org"],"Delivered-To":["patchwork-incoming@legolas.ozlabs.org","gcc-patches@gcc.gnu.org"],"Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=qualcomm.com header.i=@qualcomm.com header.a=rsa-sha256\n header.s=qcppdkim1 header.b=admGkyLl;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=oss.qualcomm.com header.i=@oss.qualcomm.com\n header.a=rsa-sha256 header.s=google header.b=BSit3WN6;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=gcc.gnu.org\n (client-ip=2620:52:6:3111::32; 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Sun, 03 May 2026\n 15:18:23 -0700 (PDT)"],"MIME-Version":"1.0","References":"<20260502180223.410876-1-avinal.xlvii@gmail.com>","In-Reply-To":"<20260502180223.410876-1-avinal.xlvii@gmail.com>","From":"Andrew Pinski ","Date":"Sun, 3 May 2026 15:18:11 -0700","X-Gm-Features":"AVHnY4IG8MPpC0xbbCy3S0ZOOsz_FWZY-iV7HHdCj5vAhcBBCPw37Pfh4-HqSpE","Message-ID":"\n ","Subject":"Re: [PATCH] match: Optimize `A > B ? ABS(A) : B` to `MAX(A, B)` when\n B >= 0 [PR116700]","To":"Avinal Kumar ","Cc":"gcc-patches@gcc.gnu.org","Content-Type":"text/plain; charset=\"UTF-8\"","Content-Transfer-Encoding":"quoted-printable","X-Proofpoint-ORIG-GUID":"nPNOopv9LWhTRAQsNgb0KJLhZgpghmKU","X-Proofpoint-Spam-Details-Enc":"AW1haW4tMjYwNTAzMDI1MiBTYWx0ZWRfX7oUzwLsEVxb1\n gIY4tXSDLnJV20L0aVbOOGMxD6LImsa3lvrsaHUQ2YQtqbvOuIsuOBrmMkb1tTO4biThJAkm0sR\n dbxG+QKNTDBbBZrD80XuXCHHjne9KLWMXhb9HVM23yZDQsXdq2Ot3Z4z4snYUE7C8J8tri5yDKv\n Wjg1L/VmTZecrDgm2ZAUyCBpl8TQcqaDWKG9aHYbeygZ7KV/ik7S2wUNAN+0dSPB4J6tVjolNfU\n AY/JxIP+rOZlFlflCYXLxE4ZOD61RrwvC1WYr3j4PW3jDlVtUmwHfYMcFl+KNLE9dZa4b4BWW14\n yGc51aLDc8tzCAwyRuoXnIZuoCSIKlIt0weERT+tkdskslPzKQkEeE6arJTAaPk7zgOIYZp6qGl\n aLCGGm6YTsVVMhNcx1rBiiVkKDt7Gyw4cErsxi2XM86x7s30yX54UvBObV8NTl8KpgaHXWCJoOT\n j6aT5N+LG3L36KSVL7Q==","X-Authority-Analysis":"v=2.4 cv=O4IJeh9W c=1 sm=1 tr=0 ts=69f7c9b1 cx=c_pps\n a=PfFC4Oe2JQzmKTvty2cRDw==:117 a=IkcTkHD0fZMA:10 a=NGcC8JguVDcA:10\n a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22\n a=Um2Pa8k9VHT-vaBCBUpS:22 a=mDV3o1hIAAAA:8 a=pGLkceISAAAA:8\n a=lRmpd4woyl_akqqaipkA:9 a=QEXdDO2ut3YA:10 a=6Ab_bkdmUrQuMsNx7PHu:22","X-Proofpoint-GUID":"nPNOopv9LWhTRAQsNgb0KJLhZgpghmKU","X-Proofpoint-Virus-Version":"vendor=baseguard\n engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49\n definitions=2026-05-03_07,2026-04-30_02,2025-10-01_01","X-Proofpoint-Spam-Details":"rule=outbound_notspam policy=outbound score=0\n lowpriorityscore=0 impostorscore=0 adultscore=0 clxscore=1015 suspectscore=0\n priorityscore=1501 malwarescore=0 spamscore=0 phishscore=0 bulkscore=0\n classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0\n reason=mlx scancount=1 engine=8.22.0-2604200000 definitions=main-2605030252","X-BeenThere":"gcc-patches@gcc.gnu.org","X-Mailman-Version":"2.1.30","Precedence":"list","List-Id":"Gcc-patches mailing list ","List-Unsubscribe":",\n ","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n ","Errors-To":"gcc-patches-bounces~incoming=patchwork.ozlabs.org@gcc.gnu.org"}},{"id":3685482,"web_url":"http://patchwork.ozlabs.org/comment/3685482/","msgid":"","list_archive_url":null,"date":"2026-05-04T02:59:25","subject":"Re: [PATCH] match: Optimize `A > B ? ABS(A) : B` to `MAX(A, B)` when\n B >= 0 [PR116700]","submitter":{"id":91428,"url":"http://patchwork.ozlabs.org/api/people/91428/","name":"Andrew Pinski","email":"andrew.pinski@oss.qualcomm.com"},"content":"On Sun, May 3, 2026 at 3:18 PM Andrew Pinski\n wrote:\n>\n> On Sat, May 2, 2026 at 11:02 AM Avinal Kumar wrote:\n> >\n> > When B is known to be non-negative and A > B, A must be positive,\n> > so ABS(A) == A. The whole expression (A > B ? ABS(A) : B) then\n> > simplifies to MAX(A, B). This is caught at -O2 via VRP, but at\n> > -O1 phiopt1 produces ABS_EXPR and no later pass simplifies it.\n> >\n> > PR tree-optimization/116700\n> >\n> > gcc/ChangeLog:\n> >\n> > * match.pd: (A > B ? ABS(A) : B -> MAX(A, B)): New pattern\n> > for non-negative B.\n> >\n> > gcc/testsuite/ChangeLog:\n> >\n> > * gcc.dg/pr116700.c: New test.\n> > * gcc.dg/tree-ssa/phi-opt-48.c: New test.\n> >\n> > Signed-off-by: Avinal Kumar \n> > ---\n> > I compared the changes in the suggested patch on bugzilla, understood patterns\n> > and tried to adapt them. The actual mechanism is still not completely understood\n> > to me. The tests are running fine but I think I am missing some cases.\n>\n> Let me go over the pattern with you (This could be used for future\n> part of the tutorials):\n> (for cmp (gt ge)\n> // this is a for loop which says cmp will either be gt (GT_EXPR,\n> greater than expression) or ge (GE_EXPR, greater than or equal\n> expression).\n> (simplify\n> // (simplify a b) means simplify the matching a into b\n> (cond (cmp:c @0 tree_expr_nonnegative_p@1) (abs @0) @1)\n> // cond here is matching COND_EXPR which is a 3 operand expressions\n> which is similar to the C operator `?:`.\n> // cmp:c means match cmp and `:c` here means to handle commutative\n> expressions in swapping the lhs and rhs operands of the expressions.\n> // But since this is a comparison, it means handling of the swapping\n> of the operands and use the corresponding comparison.\n> // That is `@0 < @1` and `@1 > @0` will match.\n> // @0/@1 are captures\n> // tree_expr_nonnegative_p is a predicate and returns true if the\n> value is nonnegative. (there are many more predicates)\n> // abs is short for ABS_EXPR which similar to the C function abs but\n> is a tree expression rather than a function call (matching\n> builtin/internal functions are supported too but we don't use them in\n> this case).\n> (if (INTEGRAL_TYPE_P (type))\n> // This says if the resulting type (type) is a scalar integral type (a\n> boolean, integer, bitint or an enum type)\n> (max @0 @1))))\n> // This is the resulting expression in this case it is max.\n>\n> >\n> > Here is how I ran the tests:\n> >\n> > make -j$(nproc)\n> > make check-gcc RUNTESTFLAGS=\"tree-ssa.exp=phi-opt-48.c\"\n> > make check-gcc RUNTESTFLAGS=\"dg.exp=pr116700.c\"\n> >\n> > On a side note, is there any trick/tips for building faster? I have a decent\n> > system (8C 16T and 64GB RAM) and it takes almost an hour.\n>\n> You can use one of the machines in the compile farm,\n> https://gcc.gnu.org/wiki/CompileFarm.\n> I will note you only ran a few testcases and not the full testsuite.\n>\n> This patch is ok, I will push it after a full bootstrap test but next\n> time you should run the full testsuite.\n\nNow pushed as r17-292-ge0c4c4cb02382b37a41da098aab3a2446d3cdf3e after\nchanging the whitespaces in the commit message to tabs for the\nchangelog entry part.\n\nThanks,\nAndrea\n\n>\n> Thanks,\n> Andrew\n>\n> >\n> > gcc/match.pd | 9 ++++++++\n> > gcc/testsuite/gcc.dg/pr116700.c | 13 +++++++++++\n> > gcc/testsuite/gcc.dg/tree-ssa/phi-opt-48.c | 25 ++++++++++++++++++++++\n> > 3 files changed, 47 insertions(+)\n> > create mode 100644 gcc/testsuite/gcc.dg/pr116700.c\n> > create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/phi-opt-48.c\n> >\n> > diff --git a/gcc/match.pd b/gcc/match.pd\n> > index dd9efb82c59..928f75c5a44 100644\n> > --- a/gcc/match.pd\n> > +++ b/gcc/match.pd\n> > @@ -7276,6 +7276,15 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)\n> > (if (INTEGRAL_TYPE_P (type))\n> > @3))\n> >\n> > +/* A > B ? ABS(A) : B -> MAX(A, B) when B is non-negative.\n> > + When A > B >= 0, A is positive so ABS(A) = A = MAX(A, B).\n> > + When A <= B, the result is B = MAX(A, B). */\n> > +(for cmp (gt ge)\n> > + (simplify\n> > + (cond (cmp:c @0 tree_expr_nonnegative_p@1) (abs @0) @1)\n> > + (if (INTEGRAL_TYPE_P (type))\n> > + (max @0 @1))))\n> > +\n> > /* (X + 1) > Y ? -X : 1 simplifies to X >= Y ? -X : 1 when\n> > X is unsigned, as when X + 1 overflows, X is -1, so -X == 1. */\n> > (simplify\n> > diff --git a/gcc/testsuite/gcc.dg/pr116700.c b/gcc/testsuite/gcc.dg/pr116700.c\n> > new file mode 100644\n> > index 00000000000..a52388249a3\n> > --- /dev/null\n> > +++ b/gcc/testsuite/gcc.dg/pr116700.c\n> > @@ -0,0 +1,13 @@\n> > +/* PR tree-optimization/116700 */\n> > +/* { dg-do compile } */\n> > +/* { dg-options \"-O1 -fdump-tree-phiopt1\" } */\n> > +\n> > +int f(unsigned char a, int b, int c)\n> > +{\n> > + int t = a;\n> > + if (c > t) t = (c > 0 ? c : -c);\n> > + return t;\n> > +}\n> > +\n> > +/* { dg-final { scan-tree-dump \"MAX_EXPR\" \"phiopt1\" } } */\n> > +/* { dg-final { scan-tree-dump-not \"ABS_EXPR\" \"phiopt1\" } } */\n> > diff --git a/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-48.c b/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-48.c\n> > new file mode 100644\n> > index 00000000000..06317766457\n> > --- /dev/null\n> > +++ b/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-48.c\n> > @@ -0,0 +1,25 @@\n> > +/* { dg-do compile } */\n> > +/* { dg-options \"-O1 -fdump-tree-phiopt1\" } */\n> > +\n> > +/* Test that (A > B) ? ABS(A) : B is simplified to MAX(A, B)\n> > + when B is known to be non-negative. */\n> > +\n> > +int f(unsigned char a, int b, int c)\n> > +{\n> > + int t = a;\n> > + if (c > t)\n> > + t = (c > 0 ? c : -c);\n> > + return t;\n> > +}\n> > +\n> > +int f1(unsigned char a, int b, int c)\n> > +{\n> > + int t = a;\n> > + if (c > t) return (c > 0 ? c : -c);\n> > + return t;\n> > +}\n> > +\n> > +/* Both functions should be converted to MAX_EXPR by phiopt1. */\n> > +/* { dg-final { scan-tree-dump-times \"MAX_EXPR\" 2 \"phiopt1\" } } */\n> > +/* { dg-final { scan-tree-dump-not \"ABS_EXPR\" \"phiopt1\" } } */\n> > +/* { dg-final { scan-tree-dump-not \"if \" \"phiopt1\" } } */\n> > --\n> > 2.54.0\n> >","headers":{"Return-Path":"","X-Original-To":["incoming@patchwork.ozlabs.org","gcc-patches@gcc.gnu.org"],"Delivered-To":["patchwork-incoming@legolas.ozlabs.org","gcc-patches@gcc.gnu.org"],"Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=qualcomm.com header.i=@qualcomm.com header.a=rsa-sha256\n header.s=qcppdkim1 header.b=KWt7vrEz;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=oss.qualcomm.com header.i=@oss.qualcomm.com\n header.a=rsa-sha256 header.s=google header.b=VFC1s3Kp;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=gcc.gnu.org\n (client-ip=2620:52:6:3111::32; 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ABS(A) : B` to `MAX(A, B)` when\n B >= 0 [PR116700]","To":"Avinal Kumar ","Cc":"gcc-patches@gcc.gnu.org","Content-Type":"text/plain; charset=\"UTF-8\"","Content-Transfer-Encoding":"quoted-printable","X-Proofpoint-GUID":"i9zxfcerh0M5l7Ts-7jAbiA_Ifn4DzEN","X-Proofpoint-ORIG-GUID":"i9zxfcerh0M5l7Ts-7jAbiA_Ifn4DzEN","X-Proofpoint-Spam-Details-Enc":"AW1haW4tMjYwNTA0MDAyOSBTYWx0ZWRfX1IlKBCCJt5Si\n m7wEEXSORhFqNQMyiVbS7/fpQUPvgZpnBxwraXTJ802DkOIW1RZytJnWmaz6ki1TOGHVDgEC0vE\n IzCgSsGqu+CB5EkymTT72xa/RePBQgy74ufbnJf1FarzOYpm+RnpQdefjU0FvpkRyw7aT0EcDAr\n vaY5DX8u1qy6yQ2XuJs9c0WSyz/An1Qesw1J0BFg5PYBQaWvL00xZG2j+mX5nf4uRFOg9/3Di6I\n JDOGDh8uK80AjNUqVd2SGGvxfgez2eiTvPDBOVhEEDdHDtyQ94ZtQd4Czs3Q6eJtV7802QaSPdb\n W4qZz+0ThkHrbb/c29RxkgyJTn4t6upXnlajLSzfIbiZvVarf4/fxV1euwkfRucdAo24/RGTzPP\n VfdmJuWiNOx2ee2AfpHKfOfqqhUsM6iwSUEHjz3D3q26c52O8Qf0ip9KruSirojIk3LSwbxBhVR\n Vel2s6UAJd7WnK7AdQQ==","X-Authority-Analysis":"v=2.4 cv=ScjHsPRu c=1 sm=1 tr=0 ts=69f80b9a cx=c_pps\n a=wEP8DlPgTf/vqF+yE6f9lg==:117 a=IkcTkHD0fZMA:10 a=NGcC8JguVDcA:10\n a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22\n a=yx91gb_oNiZeI1HMLzn7:22 a=mDV3o1hIAAAA:8 a=EUspDBNiAAAA:8 a=pGLkceISAAAA:8\n a=wd4vHVTs4SPde2T76g0A:9 a=QEXdDO2ut3YA:10 a=bBxd6f-gb0O0v-kibOvt:22","X-Proofpoint-Virus-Version":"vendor=baseguard\n engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49\n definitions=2026-05-04_01,2026-04-30_02,2025-10-01_01","X-Proofpoint-Spam-Details":"rule=outbound_notspam policy=outbound score=0\n phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 malwarescore=0\n impostorscore=0 priorityscore=1501 adultscore=0 lowpriorityscore=0\n suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc=\n route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2604200000\n definitions=main-2605040029","X-BeenThere":"gcc-patches@gcc.gnu.org","X-Mailman-Version":"2.1.30","Precedence":"list","List-Id":"Gcc-patches mailing list ","List-Unsubscribe":",\n ","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n ","Errors-To":"gcc-patches-bounces~incoming=patchwork.ozlabs.org@gcc.gnu.org"}},{"id":3685518,"web_url":"http://patchwork.ozlabs.org/comment/3685518/","msgid":"","list_archive_url":null,"date":"2026-05-04T07:04:58","subject":"Re: [PATCH] match: Optimize `A > B ? ABS(A) : B` to `MAX(A, B)` when\n B >= 0 [PR116700]","submitter":{"id":88549,"url":"http://patchwork.ozlabs.org/api/people/88549/","name":"Avinal Kumar","email":"avinal.xlvii@gmail.com"},"content":"On Mon, May 4, 2026 at 8:29 AM Andrew Pinski\n wrote:\n\n> > Let me go over the pattern with you (This could be used for future\n> > part of the tutorials):\n> > (for cmp (gt ge)\n> > // this is a for loop which says cmp will either be gt (GT_EXPR,\n> > greater than expression) or ge (GE_EXPR, greater than or equal\n> > expression).\n> > (simplify\n> > // (simplify a b) means simplify the matching a into b\n> > (cond (cmp:c @0 tree_expr_nonnegative_p@1) (abs @0) @1)\n> > // cond here is matching COND_EXPR which is a 3 operand expressions\n> > which is similar to the C operator `?:`.\n> > // cmp:c means match cmp and `:c` here means to handle commutative\n> > expressions in swapping the lhs and rhs operands of the expressions.\n> > // But since this is a comparison, it means handling of the swapping\n> > of the operands and use the corresponding comparison.\n> > // That is `@0 < @1` and `@1 > @0` will match.\n> > // @0/@1 are captures\n> > // tree_expr_nonnegative_p is a predicate and returns true if the\n> > value is nonnegative. (there are many more predicates)\n> > // abs is short for ABS_EXPR which similar to the C function abs but\n> > is a tree expression rather than a function call (matching\n> > builtin/internal functions are supported too but we don't use them in\n> > this case).\n> > (if (INTEGRAL_TYPE_P (type))\n> > // This says if the resulting type (type) is a scalar integral type (a\n> > boolean, integer, bitint or an enum type)\n> > (max @0 @1))))\n> > // This is the resulting expression in this case it is max.\n\nThanks a lot, this is very helpful.\n\n> > > Here is how I ran the tests:\n> > >\n> > > make -j$(nproc)\n> > > make check-gcc RUNTESTFLAGS=\"tree-ssa.exp=phi-opt-48.c\"\n> > > make check-gcc RUNTESTFLAGS=\"dg.exp=pr116700.c\"\n> > >\n> > > On a side note, is there any trick/tips for building faster? I have a decent\n> > > system (8C 16T and 64GB RAM) and it takes almost an hour.\n> >\n> > You can use one of the machines in the compile farm,\n> > https://gcc.gnu.org/wiki/CompileFarm.\n> > I will note you only ran a few testcases and not the full testsuite.\n> >\n> > This patch is ok, I will push it after a full bootstrap test but next\n> > time you should run the full testsuite.\n\nI ran the full testsuite as well but forgot to mention. I will mention\nit from next time.\nI have requested a CompileFarm account. 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ABS(A) : B` to `MAX(A, B)` when\n B >= 0 [PR116700]","To":"Andrew Pinski ","Cc":"gcc-patches@gcc.gnu.org","Content-Type":"text/plain; charset=\"UTF-8\"","Content-Transfer-Encoding":"quoted-printable","X-BeenThere":"gcc-patches@gcc.gnu.org","X-Mailman-Version":"2.1.30","Precedence":"list","List-Id":"Gcc-patches mailing list ","List-Unsubscribe":",\n ","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n ","Errors-To":"gcc-patches-bounces~incoming=patchwork.ozlabs.org@gcc.gnu.org"}}]