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[Committed] RISC-V: Add configure check for Zaamo/Zalrsc assembler support

Message ID 20240617165104.2529830-1-patrick@rivosinc.com
State New
Headers show
Series [Committed] RISC-V: Add configure check for Zaamo/Zalrsc assembler support | expand

Commit Message

Patrick O'Neill June 17, 2024, 4:51 p.m. UTC 
Binutils 2.42 and before don't support Zaamo/Zalrsc. Add a configure
check to prevent emitting Zaamo/Zalrsc in the arch string when the
assember does not support it.

gcc/ChangeLog:

	* common/config/riscv/riscv-common.cc
	(riscv_subset_list::to_string): Skip zaamo/zalrsc when not
	supported by the assembler.
	* config.in: Regenerate.
	* configure: Regenerate.
	* configure.ac: Add zaamo/zalrsc assmeber check.

Signed-off-by: Patrick O'Neill <patrick@rivosinc.com>
Acked-by: Palmer Dabbelt <palmer@rivosinc.com> # RISC-V
Reviewed-by: Palmer Dabbelt <palmer@rivosinc.com> # RISC-V
---
Tested using newlib rv64gc with binutils tip-of-tree and 2.42.

This results in calls being emitted when compiling for _zaamo_zalrsc
when the assember does not support these extensions.

> cat amo.c
void foo (int* bar, int* baz)
{
  __atomic_add_fetch(bar, baz, __ATOMIC_RELAXED);
}
> gcc -march=rv64id_zaamo_zalrsc -O3 amo.c
results in:
foo:
        sext.w  a1,a1
        li      a2,0
        tail    __atomic_fetch_add_4

As a result there are some testsuite failures on zalrsc specific
testcases and when using an old version of binutils on non-a targets.
Not a cause for concern imo but worth calling out.
Also testcases that check for the default isa string will fail with
the old binutils since zaamo/zalrsc aren't emitted anymore.
---
 gcc/common/config/riscv/riscv-common.cc | 11 +++++++++
 gcc/config.in                           |  6 +++++
 gcc/configure                           | 31 +++++++++++++++++++++++++
 gcc/configure.ac                        |  5 ++++
 4 files changed, 53 insertions(+)
diff mbox series

Patch

diff --git a/gcc/common/config/riscv/riscv-common.cc b/gcc/common/config/riscv/riscv-common.cc
index 78dfd6b1470..1dc1d9904c7 100644
--- a/gcc/common/config/riscv/riscv-common.cc
+++ b/gcc/common/config/riscv/riscv-common.cc
@@ -916,6 +916,7 @@  riscv_subset_list::to_string (bool version_p) const
   riscv_subset_t *subset;
 
   bool skip_zifencei = false;
+  bool skip_zaamo_zalrsc = false;
   bool skip_zicsr = false;
   bool i2p0 = false;
 
@@ -943,6 +944,10 @@  riscv_subset_list::to_string (bool version_p) const
      a mistake in that binutils 2.35 supports zicsr but not zifencei.  */
   skip_zifencei = true;
 #endif
+#ifndef HAVE_AS_MARCH_ZAAMO_ZALRSC
+  /* Skip since binutils 2.42 and earlier don't recognize zaamo/zalrsc.  */
+  skip_zaamo_zalrsc = true;
+#endif
 
   for (subset = m_head; subset != NULL; subset = subset->next)
     {
@@ -954,6 +959,12 @@  riscv_subset_list::to_string (bool version_p) const
 	  subset->name == "zicsr")
 	continue;
 
+      if (skip_zaamo_zalrsc && subset->name == "zaamo")
+	continue;
+
+      if (skip_zaamo_zalrsc && subset->name == "zalrsc")
+	continue;
+
       /* For !version_p, we only separate extension with underline for
 	 multi-letter extension.  */
       if (!first &&
diff --git a/gcc/config.in b/gcc/config.in
index e41b6dc97cd..acab3c0f126 100644
--- a/gcc/config.in
+++ b/gcc/config.in
@@ -629,6 +629,12 @@ 
 #endif
 
 
+/* Define if the assembler understands -march=rv*_zaamo_zalrsc. */
+#ifndef USED_FOR_TARGET
+#undef HAVE_AS_MARCH_ZAAMO_ZALRSC
+#endif
+
+
 /* Define if the assembler understands -march=rv*_zifencei. */
 #ifndef USED_FOR_TARGET
 #undef HAVE_AS_MARCH_ZIFENCEI
diff --git a/gcc/configure b/gcc/configure
index 94970e24051..9dc0b65dfaa 100755
--- a/gcc/configure
+++ b/gcc/configure
@@ -30820,6 +30820,37 @@  if test $gcc_cv_as_riscv_march_zifencei = yes; then
 
 $as_echo "#define HAVE_AS_MARCH_ZIFENCEI 1" >>confdefs.h
 
+fi
+
+    { $as_echo "$as_me:${as_lineno-$LINENO}: checking assembler for -march=rv32i_zaamo_zalrsc support" >&5
+$as_echo_n "checking assembler for -march=rv32i_zaamo_zalrsc support... " >&6; }
+if ${gcc_cv_as_riscv_march_zaamo_zalrsc+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  gcc_cv_as_riscv_march_zaamo_zalrsc=no
+  if test x$gcc_cv_as != x; then
+    $as_echo '' > conftest.s
+    if { ac_try='$gcc_cv_as $gcc_cv_as_flags -march=rv32i_zaamo_zalrsc -o conftest.o conftest.s >&5'
+  { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }; }
+    then
+	gcc_cv_as_riscv_march_zaamo_zalrsc=yes
+    else
+      echo "configure: failed program was" >&5
+      cat conftest.s >&5
+    fi
+    rm -f conftest.o conftest.s
+  fi
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $gcc_cv_as_riscv_march_zaamo_zalrsc" >&5
+$as_echo "$gcc_cv_as_riscv_march_zaamo_zalrsc" >&6; }
+if test $gcc_cv_as_riscv_march_zaamo_zalrsc = yes; then
+
+$as_echo "#define HAVE_AS_MARCH_ZAAMO_ZALRSC 1" >>confdefs.h
+
 fi
 
     ;;
diff --git a/gcc/configure.ac b/gcc/configure.ac
index 35475cf5aae..b2243e9954a 100644
--- a/gcc/configure.ac
+++ b/gcc/configure.ac
@@ -5452,6 +5452,11 @@  configured with --enable-newlib-nano-formatted-io.])
       [-march=rv32i_zifencei2p0],,,
       [AC_DEFINE(HAVE_AS_MARCH_ZIFENCEI, 1,
 		 [Define if the assembler understands -march=rv*_zifencei.])])
+    gcc_GAS_CHECK_FEATURE([-march=rv32i_zaamo_zalrsc support],
+      gcc_cv_as_riscv_march_zaamo_zalrsc,
+      [-march=rv32i_zaamo_zalrsc],,,
+      [AC_DEFINE(HAVE_AS_MARCH_ZAAMO_ZALRSC, 1,
+		 [Define if the assembler understands -march=rv*_zaamo_zalrsc.])])
     ;;
     loongarch*-*-*)
     gcc_GAS_CHECK_FEATURE([.dtprelword support],