From cf82d18b90fff0e7f40f646fb22a9b95283f0a06 Mon Sep 17 00:00:00 2001 Message-ID: From: Dhruv Chawla Date: Wed, 19 Nov 2025 04:55:08 -0800 Subject: [PATCH] PR tree-optimization/122733: Remove patterns for (y << x) {<,<=,>,>=} x These patterns should not be in match.pd as they require range information checks that ideally belong in VRP. They were also causing breakages as the checks weren't tight enough. Bootstrapped and regtested on aarch64-linux-gnu. Signed-off-by: Dhruv Chawla PR tree-optimization/122733 gcc/ChangeLog: * match.pd: Remove patterns. Also call constant_boolean_node instead of build_one_cst and build_zero_cst and simplify equality checking to one pattern. gcc/testsuite/ChangeLog: * gcc.dg/match-shift-cmp-1.c: Update test to only check equality. * gcc.dg/match-shift-cmp-2.c: Likewise. * gcc.dg/match-shift-cmp-3.c: Likewise. * gcc.dg/match-shift-cmp-4.c: Removed. --- gcc/match.pd | 32 ++------------- gcc/testsuite/gcc.dg/match-shift-cmp-1.c | 11 +---- gcc/testsuite/gcc.dg/match-shift-cmp-2.c | 23 ++--------- gcc/testsuite/gcc.dg/match-shift-cmp-3.c | 27 ++++++------- gcc/testsuite/gcc.dg/match-shift-cmp-4.c | 51 ------------------------ 5 files changed, 22 insertions(+), 122 deletions(-) delete mode 100644 gcc/testsuite/gcc.dg/match-shift-cmp-4.c diff --git a/gcc/match.pd b/gcc/match.pd index 63d56b081925..db774eaf696c 100644 --- a/gcc/match.pd +++ b/gcc/match.pd @@ -1339,37 +1339,13 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT) (if (INTEGRAL_TYPE_P (type)) (rshift (op @0 @2) @1)))) -/* (y << x) == x -> 0 when y != 0. */ -(simplify - (eq:c (nop_convert1? (lshift @0 @1)) (nop_convert2? @1)) - (if (INTEGRAL_TYPE_P (TREE_TYPE (@1)) - && tree_expr_nonzero_p (@0)) - { build_zero_cst (type); })) - -/* (y << x) {<,<=} x -> 0 when y > 0. */ -(for cmp (lt le) - (simplify - (cmp:c (nop_convert1? (lshift @0 @1)) (nop_convert2? @1)) - (if (INTEGRAL_TYPE_P (TREE_TYPE (@1)) - && tree_expr_nonzero_p (@0) - && tree_expr_nonnegative_p (@0)) - { build_zero_cst (type); }))) - -/* (y << x) != x -> 1 when y != 0. */ -(simplify - (ne:c (nop_convert1? (lshift @0 @1)) (nop_convert2? @1)) - (if (INTEGRAL_TYPE_P (TREE_TYPE (@1)) - && tree_expr_nonzero_p (@0)) - { build_one_cst (type); })) - -/* (y << x) {>,>=} x -> 1 when y > 0. */ -(for cmp (gt ge) +/* (y << x) == x -> false and (y << x) != x -> true when y != 0. */ +(for cmp (eq ne) (simplify (cmp:c (nop_convert1? (lshift @0 @1)) (nop_convert2? @1)) (if (INTEGRAL_TYPE_P (TREE_TYPE (@1)) - && tree_expr_nonzero_p (@0) - && tree_expr_nonnegative_p (@0)) - { build_one_cst (type); }))) + && tree_expr_nonzero_p (@0)) + { constant_boolean_node (cmp != EQ_EXPR, type); }))) /* Fold (1 << (C - x)) where C = precision(type) - 1 into ((1 << C) >> x). */ diff --git a/gcc/testsuite/gcc.dg/match-shift-cmp-1.c b/gcc/testsuite/gcc.dg/match-shift-cmp-1.c index b22d57d370f1..7a69cd194376 100644 --- a/gcc/testsuite/gcc.dg/match-shift-cmp-1.c +++ b/gcc/testsuite/gcc.dg/match-shift-cmp-1.c @@ -34,17 +34,8 @@ typedef enum TEST_OP_CST (eq, ==, 1) TEST_OP_CST (ne, !=, 2) -TEST_OP_CST (lt, <, 3) -TEST_OP_CST (gt, >, 4) -TEST_OP_CST (le, <=, 5) -TEST_OP_CST (ge, >=, 6) TEST_OP (eq, ==) TEST_OP (ne, !=) -TEST_OP (lt, <) -TEST_OP (gt, >) -TEST_OP (le, <=) -TEST_OP (ge, >=) -/* FIXME: The lt, le, gt and ge cases for int and enum don't get optimized. */ -/* { dg-final { scan-tree-dump-times "<<" 8 optimized } } */ +/* { dg-final { scan-tree-dump-not "<<" optimized } } */ diff --git a/gcc/testsuite/gcc.dg/match-shift-cmp-2.c b/gcc/testsuite/gcc.dg/match-shift-cmp-2.c index 96a2fd954f63..3d514ba1ee1b 100644 --- a/gcc/testsuite/gcc.dg/match-shift-cmp-2.c +++ b/gcc/testsuite/gcc.dg/match-shift-cmp-2.c @@ -36,27 +36,12 @@ typedef enum TEST_OP_CST (eq, ==, 0) TEST_OP_CST (ne, !=, 0) -TEST_OP_CST (lt, <, 0) -TEST_OP_CST (gt, >, 0) -TEST_OP_CST (le, <=, 0) -TEST_OP_CST (ge, >=, 0) TEST_OP (eq, ==) TEST_OP (ne, !=) -TEST_OP (lt, <) -TEST_OP (gt, >) -TEST_OP (le, <=) -TEST_OP (ge, >=) /* These end up getting folded by other patterns. */ -/* { dg-final { scan-tree-dump-times "x_\\d\\(D\\) == 0" 8 optimized } } */ -/* { dg-final { scan-tree-dump-times "x_\\d\\(D\\) != 0" 8 optimized } } */ -/* { dg-final { scan-tree-dump-times "x_\\d\\(D\\) > 0" 4 optimized } } */ -/* { dg-final { scan-tree-dump-times "x_\\d\\(D\\) < 0" 4 optimized } } */ -/* { dg-final { scan-tree-dump-times "x_\\d\\(D\\) >= 0" 4 optimized } } */ -/* { dg-final { scan-tree-dump-times "x_\\d\\(D\\) <= 0" 4 optimized } } */ -/* { dg-final { scan-tree-dump-times "~x_\\d\\(D\\)" 4 optimized } } */ -/* { dg-final { scan-tree-dump-times "return x_\\d\\(D\\);" 4 optimized } } */ -/* { dg-final { scan-tree-dump-times "return 0;" 4 optimized } } */ -/* { dg-final { scan-tree-dump-times "return 1;" 4 optimized } } */ -/* Total: 48. */ +/* { dg-final { scan-tree-dump-times "x_\\d\\(D\\) == 0" 6 optimized } } */ +/* { dg-final { scan-tree-dump-times "x_\\d\\(D\\) != 0" 6 optimized } } */ +/* { dg-final { scan-tree-dump-times "~x_\\d\\(D\\)" 2 optimized } } */ +/* { dg-final { scan-tree-dump-times "return x_\\d\\(D\\);" 2 optimized } } */ diff --git a/gcc/testsuite/gcc.dg/match-shift-cmp-3.c b/gcc/testsuite/gcc.dg/match-shift-cmp-3.c index 34380cfeb969..e46ac30b905f 100644 --- a/gcc/testsuite/gcc.dg/match-shift-cmp-3.c +++ b/gcc/testsuite/gcc.dg/match-shift-cmp-3.c @@ -1,25 +1,27 @@ /* { dg-do compile } */ /* { dg-options "-O2 -fdump-tree-optimized" } */ -/* The fold (y << x) x -> 0|1 shouldn't trigger when y is negative or - zero unsigned (except for == and !=). */ +/* The fold (y << x) x -> 0|1 should trigger when y is negative + unsigned. */ #define TEST_ONE_CST(n, op, type, cst) \ - bool lshift_cst_##type##_##n (type x) { return ((cst << x) op x); } + bool lshift_cst_##type##_##n (type x) { return ((unsigned) (cst) << x) op x; } #define TEST_OP_CST(n, op, cst) \ + TEST_ONE_CST (n, op, unsigned, cst) \ TEST_ONE_CST (n, op, int, cst) \ TEST_ONE_CST (n, op, test_enum, cst) #define TEST_ONE(n, op, type) \ bool lshift_##type##_##n (type x, type y) \ { \ - if (y > 0) \ + if ((int) y <= 0) \ __builtin_unreachable (); \ - return ((y << x) op x); \ + return ((unsigned) (y) << x) op x; \ } #define TEST_OP(n, op) \ + TEST_ONE (n, op, unsigned) \ TEST_ONE (n, op, int) \ TEST_ONE (n, op, test_enum) @@ -31,14 +33,11 @@ typedef enum TWO = 2 } test_enum; -TEST_OP_CST (lt, <, -1) -TEST_OP_CST (gt, >, -2) -TEST_OP_CST (le, <=, -3) -TEST_OP_CST (ge, >=, -4) +TEST_OP_CST (eq, ==, -1) +TEST_OP_CST (ne, !=, -2) -TEST_OP (lt, <) -TEST_OP (gt, >) -TEST_OP (le, <=) -TEST_OP (ge, >=) +TEST_OP (eq, ==) +TEST_OP (ne, !=) -/* { dg-final { scan-tree-dump-times "<<" 16 optimized } } */ +/* { dg-final { scan-tree-dump-times "return 0;" 6 optimized } } */ +/* { dg-final { scan-tree-dump-times "return 1;" 6 optimized } } */ diff --git a/gcc/testsuite/gcc.dg/match-shift-cmp-4.c b/gcc/testsuite/gcc.dg/match-shift-cmp-4.c deleted file mode 100644 index 629e2a376d11..000000000000 --- a/gcc/testsuite/gcc.dg/match-shift-cmp-4.c +++ /dev/null @@ -1,51 +0,0 @@ -/* { dg-do compile } */ -/* { dg-options "-O2 -fdump-tree-optimized" } */ - -/* The fold (y << x) x -> 0|1 should trigger when y is negative - unsigned. */ - -#define TEST_ONE_CST(n, op, type, cst) \ - bool lshift_cst_##type##_##n (type x) { return ((unsigned) (cst) << x) op x; } - -#define TEST_OP_CST(n, op, cst) \ - TEST_ONE_CST (n, op, unsigned, cst) \ - TEST_ONE_CST (n, op, int, cst) \ - TEST_ONE_CST (n, op, test_enum, cst) - -#define TEST_ONE(n, op, type) \ - bool lshift_##type##_##n (type x, type y) \ - { \ - if ((int) y <= 0) \ - __builtin_unreachable (); \ - return ((unsigned) (y) << x) op x; \ - } - -#define TEST_OP(n, op) \ - TEST_ONE (n, op, unsigned) \ - TEST_ONE (n, op, int) \ - TEST_ONE (n, op, test_enum) - -typedef enum -{ - MONE = -1, - ZERO = 0, - ONE = 1, - TWO = 2 -} test_enum; - -TEST_OP_CST (eq, ==, -1) -TEST_OP_CST (ne, !=, -2) -TEST_OP_CST (lt, <, -3) -TEST_OP_CST (gt, >, -4) -TEST_OP_CST (le, <=, -5) -TEST_OP_CST (ge, >=, -6) - -TEST_OP (eq, ==) -TEST_OP (ne, !=) -TEST_OP (lt, <) -TEST_OP (gt, >) -TEST_OP (le, <=) -TEST_OP (ge, >=) - -/* { dg-final { scan-tree-dump-times "return 0;" 18 optimized } } */ -/* { dg-final { scan-tree-dump-times "return 1;" 18 optimized } } */ base-commit: 00c16753875ddd9fcc9a6484717a1fc6dc95b691 -- 2.52.0