diff options
author | Richard Sandiford <richard.sandiford@arm.com> | 2024-10-14 09:52:44 +0100 |
---|---|---|
committer | Richard Sandiford <richard.sandiford@arm.com> | 2024-10-14 09:52:44 +0100 |
commit | 50e7c51b0a0e9dc1d93f829016ae743b4f2e5070 (patch) | |
tree | fabed8b60c05a9ec05d2b54c410038afcc72de13 | |
parent | 9f549d216c9716e787aaa38593bc9f83195b60ae (diff) | |
download | gcc-50e7c51b0a0e9dc1d93f829016ae743b4f2e5070.zip gcc-50e7c51b0a0e9dc1d93f829016ae743b4f2e5070.tar.gz gcc-50e7c51b0a0e9dc1d93f829016ae743b4f2e5070.tar.bz2 |
aarch64: Fix folding of degenerate svwhilele case [PR117045]
The svwhilele folder mishandled the degenerate case in which
the second argument is the maximum integer. In that case,
the result is all-true regardless of the first parameter:
If the second scalar operand is equal to the maximum signed integer
value then a condition which includes an equality test can never fail
and the result will be an all-true predicate.
This is because the conceptual "increment the first operand
by 1 after each element" is done modulo the range of the operand.
The GCC code was instead treating it as infinite precision.
whilele_5.c even had a test for the incorrect behaviour.
The easiest fix seemed to be to handle that case specially before
doing constant folding. This also copes with variable first operands.
gcc/
PR target/116999
PR target/117045
* config/aarch64/aarch64-sve-builtins-base.cc
(svwhilelx_impl::fold): Check for WHILELTs of the minimum value
and WHILELEs of the maximum value. Fold them to all-false and
all-true respectively.
gcc/testsuite/
PR target/116999
PR target/117045
* gcc.target/aarch64/sve/acle/general/whilele_5.c: Fix bogus
expected result.
* gcc.target/aarch64/sve/acle/general/whilele_11.c: New test.
* gcc.target/aarch64/sve/acle/general/whilele_12.c: Likewise.
4 files changed, 76 insertions, 2 deletions
diff --git a/gcc/config/aarch64/aarch64-sve-builtins-base.cc b/gcc/config/aarch64/aarch64-sve-builtins-base.cc index b189818..5210f41 100644 --- a/gcc/config/aarch64/aarch64-sve-builtins-base.cc +++ b/gcc/config/aarch64/aarch64-sve-builtins-base.cc @@ -2945,7 +2945,9 @@ public: : while_comparison (unspec_for_sint, unspec_for_uint), m_eq_p (eq_p) {} - /* Try to fold a call by treating its arguments as constants of type T. */ + /* Try to fold a call by treating its arguments as constants of type T. + We have already filtered out the degenerate cases of X .LT. MIN + and X .LE. MAX. */ template<typename T> gimple * fold_type (gimple_folder &f) const @@ -3001,6 +3003,13 @@ public: if (f.vectors_per_tuple () > 1) return nullptr; + /* Filter out cases where the condition is always true or always false. */ + tree arg1 = gimple_call_arg (f.call, 1); + if (!m_eq_p && operand_equal_p (arg1, TYPE_MIN_VALUE (TREE_TYPE (arg1)))) + return f.fold_to_pfalse (); + if (m_eq_p && operand_equal_p (arg1, TYPE_MAX_VALUE (TREE_TYPE (arg1)))) + return f.fold_to_ptrue (); + if (f.type_suffix (1).unsigned_p) return fold_type<poly_uint64> (f); else diff --git a/gcc/testsuite/gcc.target/aarch64/sve/acle/general/whilele_11.c b/gcc/testsuite/gcc.target/aarch64/sve/acle/general/whilele_11.c new file mode 100644 index 0000000..2be9dc5 --- /dev/null +++ b/gcc/testsuite/gcc.target/aarch64/sve/acle/general/whilele_11.c @@ -0,0 +1,31 @@ +/* { dg-do compile } */ +/* { dg-options "-O2" } */ + +#include <arm_sve.h> +#include <limits.h> + +svbool_t +f1 (volatile int32_t *ptr) +{ + return svwhilelt_b8_s32 (*ptr, INT32_MIN); +} + +svbool_t +f2 (volatile uint32_t *ptr) +{ + return svwhilelt_b16_u32 (*ptr, 0); +} + +svbool_t +f3 (volatile int64_t *ptr) +{ + return svwhilelt_b32_s64 (*ptr, INT64_MIN); +} + +svbool_t +f4 (volatile uint64_t *ptr) +{ + return svwhilelt_b64_u64 (*ptr, 0); +} + +/* { dg-final { scan-assembler-times {\tpfalse\tp[0-9]+\.b\n} 4 } } */ diff --git a/gcc/testsuite/gcc.target/aarch64/sve/acle/general/whilele_12.c b/gcc/testsuite/gcc.target/aarch64/sve/acle/general/whilele_12.c new file mode 100644 index 0000000..713065c --- /dev/null +++ b/gcc/testsuite/gcc.target/aarch64/sve/acle/general/whilele_12.c @@ -0,0 +1,34 @@ +/* { dg-do compile } */ +/* { dg-options "-O2" } */ + +#include <arm_sve.h> +#include <limits.h> + +svbool_t +f1 (volatile int32_t *ptr) +{ + return svwhilele_b8_s32 (*ptr, INT32_MAX); +} + +svbool_t +f2 (volatile uint32_t *ptr) +{ + return svwhilele_b16_u32 (*ptr, UINT32_MAX); +} + +svbool_t +f3 (volatile int64_t *ptr) +{ + return svwhilele_b32_s64 (*ptr, INT64_MAX); +} + +svbool_t +f4 (volatile uint64_t *ptr) +{ + return svwhilele_b64_u64 (*ptr, UINT64_MAX); +} + +/* { dg-final { scan-assembler {\tptrue\tp[0-9]+\.b(?:, all)\n} } } */ +/* { dg-final { scan-assembler {\tptrue\tp[0-9]+\.h(?:, all)\n} } } */ +/* { dg-final { scan-assembler {\tptrue\tp[0-9]+\.s(?:, all)\n} } } */ +/* { dg-final { scan-assembler {\tptrue\tp[0-9]+\.d(?:, all)\n} } } */ diff --git a/gcc/testsuite/gcc.target/aarch64/sve/acle/general/whilele_5.c b/gcc/testsuite/gcc.target/aarch64/sve/acle/general/whilele_5.c index 7c73aa5..79f0e64 100644 --- a/gcc/testsuite/gcc.target/aarch64/sve/acle/general/whilele_5.c +++ b/gcc/testsuite/gcc.target/aarch64/sve/acle/general/whilele_5.c @@ -28,7 +28,7 @@ test3 (svbool_t *ptr) *ptr = svwhilele_b16_s32 (0x7ffffffb, 0x7fffffff); } -/* { dg-final { scan-assembler {\tptrue\tp[0-9]+\.h, vl5\n} } } */ +/* { dg-final { scan-assembler {\tptrue\tp[0-9]+\.h(?:, all)\n} } } */ void test4 (svbool_t *ptr) |