Re: [PATCH] mips: Fix overaligned function arguments [PR109435]

[Jovan Dmitrovic <Jovan.Dmitrovic@Syrmia.com>]

I see what you mean now, so I've made adjustment in order for testcase to work
on assembly. Following is the updated patch.

Regards,
Jovan

From 2744357b5232c61bf1f780c4915d47b19d71f993 Mon Sep 17 00:00:00 2001
From: Jovan Dmitrovic <Jovan.Dmitrovic@Syrmia.com>
Date: Fri, 19 May 2023 12:36:55 +0200
Subject: [PATCH] mips: Fix overaligned function arguments [PR109435]

This patch changes alignment for typedef types when passed as
arguments, making the alignment equal to the alignment of
original (aliased) types.

This change makes it impossible for a typedef type to have
alignment that is less than its size.

Signed-off-by: Jovan Dmitrovic <jovan.dmitrovic@syrmia.com>

gcc/ChangeLog:
        PR target/109435
	* config/mips/mips.cc (mips_function_arg_alignment): Returns
    the alignment of function argument. In case of typedef type,
    it returns the aligment of the aliased type.
	(mips_function_arg_boundary): Relocated calculation of the
    aligment of function arguments.

gcc/testsuite/ChangeLog:
        PR target/109435
	* gcc.target/mips/align-1.c: New test.
---
 gcc/config/mips/mips.cc                 | 19 ++++++++++++-
 gcc/testsuite/gcc.target/mips/align-1.c | 38 +++++++++++++++++++++++++
 2 files changed, 56 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/gcc.target/mips/align-1.c

diff --git a/gcc/config/mips/mips.cc b/gcc/config/mips/mips.cc
index c1d1691306e..20ba35f754c 100644
--- a/gcc/config/mips/mips.cc
+++ b/gcc/config/mips/mips.cc
@@ -6190,6 +6190,23 @@ mips_arg_partial_bytes (cumulative_args_t cum, const function_arg_info &arg)
   return info.stack_words > 0 ? info.reg_words * UNITS_PER_WORD : 0;
 }
 
+/* Given MODE and TYPE of a function argument, return the alignment in
+   bits.
+   In case of typedef, alignment of its original type is
+   used.  */
+
+static unsigned int
+mips_function_arg_alignment (machine_mode mode, const_tree type)
+{
+  if (!type)
+    return GET_MODE_ALIGNMENT (mode);
+
+  if (is_typedef_decl (TYPE_NAME (type)))
+    type = DECL_ORIGINAL_TYPE (TYPE_NAME (type));
+
+  return TYPE_ALIGN (type);
+}
+
 /* Implement TARGET_FUNCTION_ARG_BOUNDARY.  Every parameter gets at
    least PARM_BOUNDARY bits of alignment, but will be given anything up
    to STACK_BOUNDARY bits if the type requires it.  */
@@ -6198,8 +6215,8 @@ static unsigned int
 mips_function_arg_boundary (machine_mode mode, const_tree type)
 {
   unsigned int alignment;
+  alignment = mips_function_arg_alignment (mode, type);
 
-  alignment = type ? TYPE_ALIGN (type) : GET_MODE_ALIGNMENT (mode);
   if (alignment < PARM_BOUNDARY)
     alignment = PARM_BOUNDARY;
   if (alignment > STACK_BOUNDARY)
diff --git a/gcc/testsuite/gcc.target/mips/align-1.c b/gcc/testsuite/gcc.target/mips/align-1.c
new file mode 100644
index 00000000000..5c639bee274
--- /dev/null
+++ b/gcc/testsuite/gcc.target/mips/align-1.c
@@ -0,0 +1,38 @@
+/* Check that typedef alignment does not affect passing of function
+   parameters. */
+/* { dg-do compile { target { "mips*-*-linux*" } } } */
+/* { dg-skip-if "" { *-*-* } { "-flto" } { "" } } */
+
+#include <assert.h>
+
+typedef struct ui8
+{
+  unsigned v[8];
+} uint8 __attribute__ ((aligned(64)));
+
+unsigned
+callee (int x, uint8 a)
+{
+  return a.v[0];
+}
+
+uint8
+identity (uint8 in)
+{
+  return in;
+}
+
+int
+main (void)
+{
+  uint8 vec = {{1, 2, 3, 4, 5, 6, 7, 8}};
+  uint8 temp = identity (vec);
+  unsigned temp2 = callee (1, identity (vec));
+  assert (callee (1, temp) == 1);
+  assert (temp2 == 1);
+  return 0;
+}
+
+/* { dg-final { scan-assembler "\tsd\t\\\$5,0\\(\\\$\[0-9\]\\)" } } */
+/* { dg-final { scan-assembler "\tsd\t\\\$6,8\\(\\\$\[0-9\]\\)" } } */
+/* { dg-final { scan-assembler "\tsd\t\\\$7,16\\(\\\$\[0-9\]\\)" } } */
-- 
2.34.1




--
YunQiang Su