[PATCH] arm: [MVE intrinsics] Fix support for loads [PR target/114323]

[Christophe Lyon]

The testcase in this PR shows that we would load from an uninitialized
location, because the vld1 instrinsics are reported as "const". This
is because function_instance::reads_global_state_p() does not take
CP_READ_MEMORY into account.  Fixing this gives vld1 the "pure"
attribute instead, and solves the problem.

2024-03-15  Christophe Lyon  <christophe.l...@linaro.org>

        PR target/114323
        gcc/
        * config/arm/arm-mve-builtins.cc
        (function_instance::reads_global_state_p): Take CP_READ_MEMORY
        into account.

        gcc/testsuite/
        * gcc.target/arm/mve/pr114323.c: New.
---
 gcc/config/arm/arm-mve-builtins.cc          |  2 +-
 gcc/testsuite/gcc.target/arm/mve/pr114323.c | 22 +++++++++++++++++++++
 2 files changed, 23 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/gcc.target/arm/mve/pr114323.c

diff --git a/gcc/config/arm/arm-mve-builtins.cc 
b/gcc/config/arm/arm-mve-builtins.cc
index 2f2c0f4a02a..6a5775c67e5 100644
--- a/gcc/config/arm/arm-mve-builtins.cc
+++ b/gcc/config/arm/arm-mve-builtins.cc
@@ -746,7 +746,7 @@ function_instance::reads_global_state_p () const
   if (flags & CP_READ_FPCR)
     return true;
 
-  return false;
+  return flags & CP_READ_MEMORY;
 }
 
 /* Return true if calls to the function could modify some form of
diff --git a/gcc/testsuite/gcc.target/arm/mve/pr114323.c 
b/gcc/testsuite/gcc.target/arm/mve/pr114323.c
new file mode 100644
index 00000000000..bd9127b886a
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/mve/pr114323.c
@@ -0,0 +1,22 @@
+/* { dg-do run } */
+/* { dg-require-effective-target arm_mve_hw } */
+/* { dg-options "-O2" } */
+/* { dg-add-options arm_v8_1m_mve_fp } */
+
+#include <arm_mve.h>
+
+__attribute__((noipa))
+uint32x4_t foo (void) {
+  uint32x4_t V0 = vld1q_u32(((const uint32_t[4]){1, 2, 3, 4}));
+  return V0;
+}
+
+int main(void)
+{
+  uint32_t buf[4];
+ vst1q_u32 (buf, foo());
+
+  for (int i = 0; i < 4; i++)
+    if (buf[i] != i+1)
+      __builtin_abort ();
+}
-- 
2.34.1