RISC-V: Allow adding enabled extension via target arch attributes

The set of enabled extensions can be extended via target arch function
attributes by listing each extension with a '+' prefix and a comma as
list separator.  E.g.:
  __attribute__((target("arch=+zba,+zbb"))) void foo();

The programmer intends to ensure that one or more extensions
are enabled when building the code.  This is independent of the arch
string that is passed at build time via the -march= option.

Therefore, it is reasonable to allow enabling extensions via target arch
attributes, which have already been enabled via the -march= string.

The subset list code already supports such duplication for implied
extensions.  This patch adds an interface so the subset list
parser can be switched into a mode where duplication is allowed.

This commit fixes the following regressed test cases:
* gcc.target/riscv/rvv/base/target_attribute_v_with_intrinsic-39.c
* gcc.target/riscv/rvv/base/target_attribute_v_with_intrinsic-42.c
* gcc.target/riscv/rvv/base/target_attribute_v_with_intrinsic-43.c
* gcc.target/riscv/rvv/base/target_attribute_v_with_intrinsic-44.c
* gcc.target/riscv/rvv/base/target_attribute_v_with_intrinsic-45.c
* gcc.target/riscv/rvv/base/target_attribute_v_with_intrinsic-46.c

gcc/ChangeLog:

	* common/config/riscv/riscv-common.cc (riscv_subset_list::add):
	Allow adding enabled extension if m_allow_adding_dup is set.
	* config/riscv/riscv-subset.h: Add m_allow_adding_dup and setter.
	* config/riscv/riscv-target-attr.cc (riscv_target_attr_parser::parse_arch):
	Allow adding enabled extensions.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/pr115554.c: Change expected fail to expected pass.
	* gcc.target/riscv/target-attr-16.c: New test.

Signed-off-by: Christoph Müllner <christoph.muellner@vrull.eu>

5 files changed, 47 insertions, 8 deletions

diff --git a/gcc/common/config/riscv/riscv-common.cc b/gcc/common/config/riscv/riscv-common.cc
index 8e9beb6..682826c 100644
--- a/gcc/common/config/riscv/riscv-common.cc
+++ b/gcc/common/config/riscv/riscv-common.cc
@@ -702,12 +702,17 @@ riscv_subset_list::add (const char *subset, int major_version,
 	  ext->minor_version = minor_version;
 	}
       else
-	error_at (
-	  m_loc,
-	  "%<-march=%s%>: extension %qs appear more than one time",
-	  m_arch,
-	  subset);
-
+	{
+	  /* The extension is already in the list.  */
+	  if (!m_allow_adding_dup
+	      || ext->major_version != major_version
+	      || ext->minor_version != minor_version)
+	    error_at (
+	      m_loc,
+	      "%<-march=%s%>: extension %qs appear more than one time",
+	      m_arch,
+	      subset);
+	}
       return;
     }
   else if (strlen (subset) == 1 && !standard_extensions_p (subset))
diff --git a/gcc/config/riscv/riscv-subset.h b/gcc/config/riscv/riscv-subset.h
index 279716f..dace4de 100644
--- a/gcc/config/riscv/riscv-subset.h
+++ b/gcc/config/riscv/riscv-subset.h
@@ -65,6 +65,9 @@ private:
   /* Number of subsets. */
   unsigned m_subset_num;
 
+  /* Allow adding the same extension more than once.  */
+  bool m_allow_adding_dup;
+
   riscv_subset_list (const char *, location_t);
 
   const char *parsing_subset_version (const char *, const char *, unsigned *,
@@ -109,6 +112,8 @@ public:
 
   void set_loc (location_t);
 
+  void set_allow_adding_dup (bool v) { m_allow_adding_dup = v; }
+
   void finalize ();
 };
 
diff --git a/gcc/config/riscv/riscv-target-attr.cc b/gcc/config/riscv/riscv-target-attr.cc
index 3178061..57235c9 100644
--- a/gcc/config/riscv/riscv-target-attr.cc
+++ b/gcc/config/riscv/riscv-target-attr.cc
@@ -109,6 +109,8 @@ riscv_target_attr_parser::parse_arch (const char *str)
 		      ? riscv_subset_list::parse (local_arch_str, m_loc)
 		      : riscv_cmdline_subset_list ()->clone ();
       m_subset_list->set_loc (m_loc);
+      m_subset_list->set_allow_adding_dup (true);
+
       while (token)
 	{
 	  if (token[0] != '+')
@@ -134,6 +136,7 @@ riscv_target_attr_parser::parse_arch (const char *str)
 	  token = strtok_r (NULL, ",", &str_to_check);
 	}
 
+      m_subset_list->set_allow_adding_dup (false);
       m_subset_list->finalize ();
       return true;
     }
diff --git a/gcc/testsuite/gcc.target/riscv/pr115554.c b/gcc/testsuite/gcc.target/riscv/pr115554.c
index e7dcde6..16d5f63 100644
--- a/gcc/testsuite/gcc.target/riscv/pr115554.c
+++ b/gcc/testsuite/gcc.target/riscv/pr115554.c
@@ -9,5 +9,3 @@ extern
 __attribute__((target("arch=+zbb")))
 __attribute__((target("arch=+zbb")))
 void bar(void);
-
-/* { dg-error "extension 'zbb' appear more than one time" "" { target *-*-* } 0 } */
diff --git a/gcc/testsuite/gcc.target/riscv/target-attr-16.c b/gcc/testsuite/gcc.target/riscv/target-attr-16.c
new file mode 100644
index 0000000..1c7badc
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/target-attr-16.c
@@ -0,0 +1,28 @@
+/* { dg-do compile } */
+/* { dg-options "-march=rv32gc_zba" { target { rv32 } } } */
+/* { dg-options "-march=rv64gc_zba" { target { rv64 } } } */
+
+__attribute__((target("arch=+zba,+zbb")))
+void foo1 (void)
+{
+}
+
+__attribute__((target("arch=+zbb,+zbb")))
+void foo2 (void)
+{
+}
+
+__attribute__((target("arch=+zba")))
+__attribute__((target("arch=+zbb")))
+void foo (void)
+{
+}
+
+__attribute__((target("arch=+zbb")))
+__attribute__((target("arch=+zbb")))
+void bar (void)
+{
+}
+
+/* { dg-final { scan-assembler-times ".option arch, rv32i2p1_m2p0_a2p1_f2p2_d2p2_c2p0_zicsr2p0_zifencei2p0_zaamo1p0_zalrsc1p0_zca1p0_zcd1p0_zba1p0_zbb1p0" 4 { target { rv32 } } } } */
+/* { dg-final { scan-assembler-times ".option arch, rv64i2p1_m2p0_a2p1_f2p2_d2p2_c2p0_zicsr2p0_zifencei2p0_zaamo1p0_zalrsc1p0_zca1p0_zcd1p0_zba1p0_zbb1p0" 4 { target { rv64 } } } } */