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authorRichard Sandiford <richard.sandiford@arm.com>2024-10-14 09:52:44 +0100
committerRichard Sandiford <richard.sandiford@arm.com>2024-10-14 09:52:44 +0100
commit50e7c51b0a0e9dc1d93f829016ae743b4f2e5070 (patch)
treefabed8b60c05a9ec05d2b54c410038afcc72de13
parent9f549d216c9716e787aaa38593bc9f83195b60ae (diff)
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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.
-rw-r--r--gcc/config/aarch64/aarch64-sve-builtins-base.cc11
-rw-r--r--gcc/testsuite/gcc.target/aarch64/sve/acle/general/whilele_11.c31
-rw-r--r--gcc/testsuite/gcc.target/aarch64/sve/acle/general/whilele_12.c34
-rw-r--r--gcc/testsuite/gcc.target/aarch64/sve/acle/general/whilele_5.c2
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)