Re: [PATCH] riscv: generate builtin macro for compilation with strict alignment

2023-04-28 Thread Vineet Gupta 




On 4/20/23 09:56, Jeff Law via Gcc-patches wrote:



On 1/17/23 15:59, Vineet Gupta wrote:

This could be useful for library writers who want to write code variants
for fast vs. slow unaligned accesses.

We distinguish explicit -mstrict-align (1) vs. slow_unaligned_access
cpu tune param (2) for even more code divesity.

gcc/ChangeLog:

* config/riscv-c.cc (riscv_cpu_cpp_builtins):
  Generate __riscv_strict_align with value 1 or 2.
* config/riscv/riscv.cc: Define riscv_user_wants_strict_align.
  (riscv_option_override) Set riscv_user_wants_strict_align to
  TARGET_STRICT_ALIGN.
* config/riscv/riscv.h: Declare riscv_user_wants_strict_align.

gcc/testsuite/ChangeLog:

* gcc.target/riscv/attribute.c: Check for
  __riscv_strict_align=1.
* gcc.target/riscv/predef-align-1.c: New test.
* gcc.target/riscv/predef-align-2.c: New test.
* gcc.target/riscv/predef-align-3.c: New test.
* gcc.target/riscv/predef-align-4.c: New test.
* gcc.target/riscv/predef-align-5.c: New test.

Signed-off-by: Vineet Gupta 
---
  gcc/config/riscv/riscv-c.cc | 11 +++
  gcc/config/riscv/riscv.cc   |  9 +
  gcc/config/riscv/riscv.h    |  1 +
  gcc/testsuite/gcc.target/riscv/attribute-4.c    |  9 +
  gcc/testsuite/gcc.target/riscv/predef-align-1.c | 12 
  gcc/testsuite/gcc.target/riscv/predef-align-2.c | 11 +++
  gcc/testsuite/gcc.target/riscv/predef-align-3.c | 15 +++
  gcc/testsuite/gcc.target/riscv/predef-align-4.c | 16 
  gcc/testsuite/gcc.target/riscv/predef-align-5.c | 16 
  9 files changed, 100 insertions(+)
  create mode 100644 gcc/testsuite/gcc.target/riscv/predef-align-1.c
  create mode 100644 gcc/testsuite/gcc.target/riscv/predef-align-2.c
  create mode 100644 gcc/testsuite/gcc.target/riscv/predef-align-3.c
  create mode 100644 gcc/testsuite/gcc.target/riscv/predef-align-4.c
  create mode 100644 gcc/testsuite/gcc.target/riscv/predef-align-5.c

diff --git a/gcc/config/riscv/riscv-c.cc b/gcc/config/riscv/riscv-c.cc
index 826ae0067bb8..47a396501d74 100644
--- a/gcc/config/riscv/riscv-c.cc
+++ b/gcc/config/riscv/riscv-c.cc
@@ -102,6 +102,17 @@ riscv_cpu_cpp_builtins (cpp_reader *pfile)
    }
  +  /* TARGET_STRICT_ALIGN does not cover all cases.  */
+  if (riscv_slow_unaligned_access_p)
+    {
+  /* Explicit -mstruct-align preceedes cpu tune param
+ slow_unaligned_access=true.  */

Did you mean "-mstrict-align" above?


Doh sorry yes.





+  if (riscv_user_wants_strict_align)
+    builtin_define_with_int_value ("__riscv_strict_align", 1);
+  else
+    builtin_define_with_int_value ("__riscv_strict_align", 2);
So I don't understand why we're testing 
"riscv_user_wants_strict_align" instead of TARGET_STRICT_ALIGN here.  
AFAICT they're equivalent.  But maybe there's something subtle I'm 
missing.


The missing part is slightly over-engineered unaligned access signaling 
in RV gcc frontend IMHO.


Thing is -mno-strict-align can be over-ruled by the cpu tune param 
slow_unaligned_access=true (and behave as if -mstrict-align was passed)
And I wanted the macro to reflect this (for future proofing) by being 
defined but with different values.


There's some renewed discussion with Kito on [1] so I need to respin 
this after getting the agreed upon specification in there.


Thx,
-Vineet

[1] https://github.com/riscv-non-isa/riscv-c-api-doc/issues/32

Re: [PATCH] riscv: generate builtin macro for compilation with strict alignment

2023-04-20 Thread Jeff Law via Gcc-patches 




On 1/17/23 15:59, Vineet Gupta wrote:

This could be useful for library writers who want to write code variants
for fast vs. slow unaligned accesses.

We distinguish explicit -mstrict-align (1) vs. slow_unaligned_access
cpu tune param (2) for even more code divesity.

gcc/ChangeLog:

* config/riscv-c.cc (riscv_cpu_cpp_builtins):
  Generate __riscv_strict_align with value 1 or 2.
* config/riscv/riscv.cc: Define riscv_user_wants_strict_align.
  (riscv_option_override) Set riscv_user_wants_strict_align to
  TARGET_STRICT_ALIGN.
* config/riscv/riscv.h: Declare riscv_user_wants_strict_align.

gcc/testsuite/ChangeLog:

* gcc.target/riscv/attribute.c: Check for
  __riscv_strict_align=1.
* gcc.target/riscv/predef-align-1.c: New test.
* gcc.target/riscv/predef-align-2.c: New test.
* gcc.target/riscv/predef-align-3.c: New test.
* gcc.target/riscv/predef-align-4.c: New test.
* gcc.target/riscv/predef-align-5.c: New test.

Signed-off-by: Vineet Gupta 
---
  gcc/config/riscv/riscv-c.cc | 11 +++
  gcc/config/riscv/riscv.cc   |  9 +
  gcc/config/riscv/riscv.h|  1 +
  gcc/testsuite/gcc.target/riscv/attribute-4.c|  9 +
  gcc/testsuite/gcc.target/riscv/predef-align-1.c | 12 
  gcc/testsuite/gcc.target/riscv/predef-align-2.c | 11 +++
  gcc/testsuite/gcc.target/riscv/predef-align-3.c | 15 +++
  gcc/testsuite/gcc.target/riscv/predef-align-4.c | 16 
  gcc/testsuite/gcc.target/riscv/predef-align-5.c | 16 
  9 files changed, 100 insertions(+)
  create mode 100644 gcc/testsuite/gcc.target/riscv/predef-align-1.c
  create mode 100644 gcc/testsuite/gcc.target/riscv/predef-align-2.c
  create mode 100644 gcc/testsuite/gcc.target/riscv/predef-align-3.c
  create mode 100644 gcc/testsuite/gcc.target/riscv/predef-align-4.c
  create mode 100644 gcc/testsuite/gcc.target/riscv/predef-align-5.c

diff --git a/gcc/config/riscv/riscv-c.cc b/gcc/config/riscv/riscv-c.cc
index 826ae0067bb8..47a396501d74 100644
--- a/gcc/config/riscv/riscv-c.cc
+++ b/gcc/config/riscv/riscv-c.cc
@@ -102,6 +102,17 @@ riscv_cpu_cpp_builtins (cpp_reader *pfile)
  
  }
  
+  /* TARGET_STRICT_ALIGN does not cover all cases.  */

+  if (riscv_slow_unaligned_access_p)
+{
+  /* Explicit -mstruct-align preceedes cpu tune param
+ slow_unaligned_access=true.  */

Did you mean "-mstrict-align" above?



+  if (riscv_user_wants_strict_align)
+builtin_define_with_int_value ("__riscv_strict_align", 1);
+  else
+builtin_define_with_int_value ("__riscv_strict_align", 2);
So I don't understand why we're testing "riscv_user_wants_strict_align" 
instead of TARGET_STRICT_ALIGN here.  AFAICT they're equivalent.  But 
maybe there's something subtle I'm missing.


Jeff

[PATCH] riscv: generate builtin macro for compilation with strict alignment

2023-01-17 Thread Vineet Gupta 
This could be useful for library writers who want to write code variants
for fast vs. slow unaligned accesses.

We distinguish explicit -mstrict-align (1) vs. slow_unaligned_access
cpu tune param (2) for even more code divesity.

gcc/ChangeLog:

* config/riscv-c.cc (riscv_cpu_cpp_builtins):
  Generate __riscv_strict_align with value 1 or 2.
* config/riscv/riscv.cc: Define riscv_user_wants_strict_align.
  (riscv_option_override) Set riscv_user_wants_strict_align to
  TARGET_STRICT_ALIGN.
* config/riscv/riscv.h: Declare riscv_user_wants_strict_align.

gcc/testsuite/ChangeLog:

* gcc.target/riscv/attribute.c: Check for
  __riscv_strict_align=1.
* gcc.target/riscv/predef-align-1.c: New test.
* gcc.target/riscv/predef-align-2.c: New test.
* gcc.target/riscv/predef-align-3.c: New test.
* gcc.target/riscv/predef-align-4.c: New test.
* gcc.target/riscv/predef-align-5.c: New test.

Signed-off-by: Vineet Gupta 
---
 gcc/config/riscv/riscv-c.cc | 11 +++
 gcc/config/riscv/riscv.cc   |  9 +
 gcc/config/riscv/riscv.h|  1 +
 gcc/testsuite/gcc.target/riscv/attribute-4.c|  9 +
 gcc/testsuite/gcc.target/riscv/predef-align-1.c | 12 
 gcc/testsuite/gcc.target/riscv/predef-align-2.c | 11 +++
 gcc/testsuite/gcc.target/riscv/predef-align-3.c | 15 +++
 gcc/testsuite/gcc.target/riscv/predef-align-4.c | 16 
 gcc/testsuite/gcc.target/riscv/predef-align-5.c | 16 
 9 files changed, 100 insertions(+)
 create mode 100644 gcc/testsuite/gcc.target/riscv/predef-align-1.c
 create mode 100644 gcc/testsuite/gcc.target/riscv/predef-align-2.c
 create mode 100644 gcc/testsuite/gcc.target/riscv/predef-align-3.c
 create mode 100644 gcc/testsuite/gcc.target/riscv/predef-align-4.c
 create mode 100644 gcc/testsuite/gcc.target/riscv/predef-align-5.c

diff --git a/gcc/config/riscv/riscv-c.cc b/gcc/config/riscv/riscv-c.cc
index 826ae0067bb8..47a396501d74 100644
--- a/gcc/config/riscv/riscv-c.cc
+++ b/gcc/config/riscv/riscv-c.cc
@@ -102,6 +102,17 @@ riscv_cpu_cpp_builtins (cpp_reader *pfile)
 
 }
 
+  /* TARGET_STRICT_ALIGN does not cover all cases.  */
+  if (riscv_slow_unaligned_access_p)
+{
+  /* Explicit -mstruct-align preceedes cpu tune param
+ slow_unaligned_access=true.  */
+  if (riscv_user_wants_strict_align)
+builtin_define_with_int_value ("__riscv_strict_align", 1);
+  else
+builtin_define_with_int_value ("__riscv_strict_align", 2);
+}
+
   if (TARGET_MIN_VLEN != 0)
 builtin_define_with_int_value ("__riscv_v_min_vlen", TARGET_MIN_VLEN);
 
diff --git a/gcc/config/riscv/riscv.cc b/gcc/config/riscv/riscv.cc
index 9a53999a39de..d6a40d043584 100644
--- a/gcc/config/riscv/riscv.cc
+++ b/gcc/config/riscv/riscv.cc
@@ -255,6 +255,9 @@ struct riscv_tune_info {
 /* Whether unaligned accesses execute very slowly.  */
 bool riscv_slow_unaligned_access_p;
 
+/* Whether use explcitly passed -mstrict-align.  */
+bool riscv_user_wants_strict_align;
+
 /* Stack alignment to assume/maintain.  */
 unsigned riscv_stack_boundary;
 
@@ -6047,6 +6050,12 @@ riscv_option_override (void)
  -m[no-]strict-align is left unspecified, heed -mtune's advice.  */
   riscv_slow_unaligned_access_p = (cpu->tune_param->slow_unaligned_access
   || TARGET_STRICT_ALIGN);
+
+  /* Make a note if user explicitly passed -mstrict-align for later
+ builtin macro generation. Can't use  target_flags_explicit since
+ it is set even for -mno-strict-align.  */
+  riscv_user_wants_strict_align = TARGET_STRICT_ALIGN;
+
   if ((target_flags_explicit & MASK_STRICT_ALIGN) == 0
   && cpu->tune_param->slow_unaligned_access)
 target_flags |= MASK_STRICT_ALIGN;
diff --git a/gcc/config/riscv/riscv.h b/gcc/config/riscv/riscv.h
index 0ab739bd6ebf..c55546656b7d 100644
--- a/gcc/config/riscv/riscv.h
+++ b/gcc/config/riscv/riscv.h
@@ -1030,6 +1030,7 @@ while (0)
 #ifndef USED_FOR_TARGET
 extern const enum reg_class riscv_regno_to_class[];
 extern bool riscv_slow_unaligned_access_p;
+extern bool riscv_user_wants_strict_align;
 extern unsigned riscv_stack_boundary;
 extern unsigned riscv_bytes_per_vector_chunk;
 extern poly_uint16 riscv_vector_chunks;
diff --git a/gcc/testsuite/gcc.target/riscv/attribute-4.c 
b/gcc/testsuite/gcc.target/riscv/attribute-4.c
index 7c565c4963ec..ce7f1929e6a6 100644
--- a/gcc/testsuite/gcc.target/riscv/attribute-4.c
+++ b/gcc/testsuite/gcc.target/riscv/attribute-4.c
@@ -2,5 +2,14 @@
 /* { dg-options "-mriscv-attribute -mstrict-align" } */
 int foo()
 {
+
+#if !defined(__riscv_strict_align)
+#error "__riscv_strict_align"
+#if __riscv_strict_align != 1
+#error "__riscv_strict_align != 1"
+#endif
+#endif
+
+  return 0;
 }
 /* { dg-final { scan-assembler ".attribute unaligned_access, 0" } } */
diff --git