[PATCH v2] AArch64: Cleanup CPU option processing code

Wilco Dijkstra Wilco.Dijkstra@arm.com
Thu Nov 4 14:16:28 GMT 2021


v2: rebased

The --with-cpu/--with-arch configure option processing not only checks valid arguments
but also sets TARGET_CPU_DEFAULT with a CPU and extension bitmask.  This isn't used
however since a --with-cpu is translated into a -mcpu option which is processed as if
written on the command-line (so TARGET_CPU_DEFAULT is never accessed).

So remove all the complex processing and bitmask, and just validate the option.
Fix a bug that always reports valid architecture extensions as invalid.  As a result
the CPU processing in aarch64.c can be simplified.

Bootstrap OK, regress pass, OK for commit?

ChangeLog:
2020-09-03  Wilco Dijkstra  <wdijkstr@arm.com>

        * config.gcc (aarch64*-*-*): Simplify --with-cpu and --with-arch
        processing.  Add support for architectural extensions.
        * config/aarch64/aarch64.h (TARGET_CPU_DEFAULT): Remove
        AARCH64_CPU_DEFAULT_FLAGS.
        * config/aarch64/aarch64.c (AARCH64_CPU_DEFAULT_FLAGS): Remove define.
        (get_tune_cpu): Assert CPU is always valid.
        (get_arch): Assert architecture is always valid.
        (aarch64_override_options): Cleanup CPU selection code and simplify logic.

---

diff --git a/gcc/config.gcc b/gcc/config.gcc
index aa5bd5d14590e38dcee979f236e60c2505a789f9..25b0fa30a2b7cae4bf1e617db9dd70d9b321eeda 100644
--- a/gcc/config.gcc
+++ b/gcc/config.gcc
@@ -4146,8 +4146,6 @@ case "${target}" in
 			  pattern=AARCH64_CORE
 			fi
 
-			ext_mask=AARCH64_CPU_DEFAULT_FLAGS
-
 			# Find the base CPU or ARCH id in aarch64-cores.def or
 			# aarch64-arches.def
 			if [ x"$base_val" = x ] \
@@ -4155,23 +4153,6 @@ case "${target}" in
 				    ${srcdir}/config/aarch64/$def \
 				    > /dev/null; then
 
-			  if [ $which = arch ]; then
-				base_id=`grep "^$pattern(\"$base_val\"," \
-				  ${srcdir}/config/aarch64/$def | \
-				  sed -e 's/^[^,]*,[ 	]*//' | \
-				  sed -e 's/,.*$//'`
-				# Extract the architecture flags from aarch64-arches.def
-				ext_mask=`grep "^$pattern(\"$base_val\"," \
-				   ${srcdir}/config/aarch64/$def | \
-				   sed -e 's/)$//' | \
-				   sed -e 's/^.*,//'`
-			  else
-				base_id=`grep "^$pattern(\"$base_val\"," \
-				  ${srcdir}/config/aarch64/$def | \
-				  sed -e 's/^[^,]*,[ 	]*//' | \
-				  sed -e 's/,.*$//'`
-			  fi
-
 			  # Disallow extensions in --with-tune=cortex-a53+crc.
 			  if [ $which = tune ] && [ x"$ext_val" != x ]; then
 			    echo "Architecture extensions not supported in --with-$which=$val" 1>&2
@@ -4202,25 +4183,7 @@ case "${target}" in
 					grep "^\"$base_ext\""`
 
 				if [ x"$base_ext" = x ] \
-				    || [[ -n $opt_line ]]; then
-
-				  # These regexp extract the elements based on
-				  # their group match index in the regexp.
-				  ext_canon=`echo -e "$opt_line" | \
-					sed -e "s/$sed_patt/\2/"`
-				  ext_on=`echo -e "$opt_line" | \
-					sed -e "s/$sed_patt/\3/"`
-				  ext_off=`echo -e "$opt_line" | \
-					sed -e "s/$sed_patt/\4/"`
-
-				  if [ $ext = $base_ext ]; then
-					# Adding extension
-					ext_mask="("$ext_mask") | ("$ext_on" | "$ext_canon")"
-				  else
-					# Removing extension
-					ext_mask="("$ext_mask") & ~("$ext_off" | "$ext_canon")"
-				  fi
-
+				    || [ x"$opt_line" != x ]; then
 				  true
 				else
 				  echo "Unknown extension used in --with-$which=$val" 1>&2
@@ -4229,10 +4192,6 @@ case "${target}" in
 				ext_val=`echo $ext_val | sed -e 's/[a-z0-9]\+//'`
 			  done
 
-			  ext_mask="(("$ext_mask") << 6)"
-			  if [ x"$base_id" != x ]; then
-				target_cpu_cname="TARGET_CPU_$base_id | $ext_mask"
-			  fi
 			  true
 			else
 			  # Allow --with-$which=native.
diff --git a/gcc/config/aarch64/aarch64.h b/gcc/config/aarch64/aarch64.h
index 2792bb29adbbb5b3145b3f767615af8edbc30b08..c1cd0a9f6ce83a99dc4d5e7ab2cecd463ad06e08 100644
--- a/gcc/config/aarch64/aarch64.h
+++ b/gcc/config/aarch64/aarch64.h
@@ -798,8 +798,7 @@ enum target_cpus
 
 /* If there is no CPU defined at configure, use generic as default.  */
 #ifndef TARGET_CPU_DEFAULT
-#define TARGET_CPU_DEFAULT \
-  (TARGET_CPU_generic | (AARCH64_CPU_DEFAULT_FLAGS << 6))
+# define TARGET_CPU_DEFAULT TARGET_CPU_generic
 #endif
 
 /* If inserting NOP before a mult-accumulate insn remember to adjust the
diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index ab2954d11333b3f5a419c55d0a74f13d1df70680..430ea036a7be4da842fd08998923a3462457dbfd 100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -2135,8 +2135,6 @@ static const struct attribute_spec aarch64_attribute_table[] =
   { NULL,                 0, 0, false, false, false, false, NULL, NULL }
 };
 
-#define AARCH64_CPU_DEFAULT_FLAGS ((selected_cpu) ? selected_cpu->flags : 0)
-
 /* An ISA extension in the co-processor and main instruction set space.  */
 struct aarch64_option_extension
 {
@@ -16930,35 +16928,24 @@ aarch64_validate_mtune (const char *str, const struct processor **res)
   return false;
 }
 
-/* Return the CPU corresponding to the enum CPU.
-   If it doesn't specify a cpu, return the default.  */
+/* Return the CPU corresponding to the enum CPU.  */
 
 static const struct processor *
 aarch64_get_tune_cpu (enum aarch64_processor cpu)
 {
-  if (cpu != aarch64_none)
-    return &all_cores[cpu];
+  gcc_assert (cpu != aarch64_none);
 
-  /* The & 0x3f is to extract the bottom 6 bits that encode the
-     default cpu as selected by the --with-cpu GCC configure option
-     in config.gcc.
-     ???: The whole TARGET_CPU_DEFAULT and AARCH64_CPU_DEFAULT_FLAGS
-     flags mechanism should be reworked to make it more sane.  */
-  return &all_cores[TARGET_CPU_DEFAULT & 0x3f];
+  return &all_cores[cpu];
 }
 
-/* Return the architecture corresponding to the enum ARCH.
-   If it doesn't specify a valid architecture, return the default.  */
+/* Return the architecture corresponding to the enum ARCH.  */
 
 static const struct processor *
 aarch64_get_arch (enum aarch64_arch arch)
 {
-  if (arch != aarch64_no_arch)
-    return &all_architectures[arch];
-
-  const struct processor *cpu = &all_cores[TARGET_CPU_DEFAULT & 0x3f];
+  gcc_assert (arch != aarch64_no_arch);
 
-  return &all_architectures[cpu->arch];
+  return &all_architectures[arch];
 }
 
 /* Return the VG value associated with -msve-vector-bits= value VALUE.  */
@@ -16996,10 +16983,6 @@ aarch64_override_options (void)
   uint64_t arch_isa = 0;
   aarch64_isa_flags = 0;
 
-  bool valid_cpu = true;
-  bool valid_tune = true;
-  bool valid_arch = true;
-
   selected_cpu = NULL;
   selected_arch = NULL;
   selected_tune = NULL;
@@ -17014,77 +16997,56 @@ aarch64_override_options (void)
      If either of -march or -mtune is given, they override their
      respective component of -mcpu.  */
   if (aarch64_cpu_string)
-    valid_cpu = aarch64_validate_mcpu (aarch64_cpu_string, &selected_cpu,
-					&cpu_isa);
+    aarch64_validate_mcpu (aarch64_cpu_string, &selected_cpu, &cpu_isa);
 
   if (aarch64_arch_string)
-    valid_arch = aarch64_validate_march (aarch64_arch_string, &selected_arch,
-					  &arch_isa);
+    aarch64_validate_march (aarch64_arch_string, &selected_arch, &arch_isa);
 
   if (aarch64_tune_string)
-    valid_tune = aarch64_validate_mtune (aarch64_tune_string, &selected_tune);
+    aarch64_validate_mtune (aarch64_tune_string, &selected_tune);
 
 #ifdef SUBTARGET_OVERRIDE_OPTIONS
   SUBTARGET_OVERRIDE_OPTIONS;
 #endif
 
-  /* If the user did not specify a processor, choose the default
-     one for them.  This will be the CPU set during configuration using
-     --with-cpu, otherwise it is "generic".  */
-  if (!selected_cpu)
-    {
-      if (selected_arch)
-	{
-	  selected_cpu = &all_cores[selected_arch->ident];
-	  aarch64_isa_flags = arch_isa;
-	  explicit_arch = selected_arch->arch;
-	}
-      else
-	{
-	  /* Get default configure-time CPU.  */
-	  selected_cpu = aarch64_get_tune_cpu (aarch64_none);
-	  aarch64_isa_flags = TARGET_CPU_DEFAULT >> 6;
-	}
-
-      if (selected_tune)
-	explicit_tune_core = selected_tune->ident;
-    }
-  /* If both -mcpu and -march are specified check that they are architecturally
-     compatible, warn if they're not and prefer the -march ISA flags.  */
-  else if (selected_arch)
+  if (selected_cpu && selected_arch)
     {
+      /* If both -mcpu and -march are specified, warn if they are not
+	 architecturally compatible and prefer the -march ISA flags.  */
       if (selected_arch->arch != selected_cpu->arch)
 	{
 	  warning (0, "switch %<-mcpu=%s%> conflicts with %<-march=%s%> switch",
 		       aarch64_cpu_string,
 		       aarch64_arch_string);
 	}
+
       aarch64_isa_flags = arch_isa;
-      explicit_arch = selected_arch->arch;
-      explicit_tune_core = selected_tune ? selected_tune->ident
-					  : selected_cpu->ident;
     }
-  else
+  else if (selected_cpu)
     {
-      /* -mcpu but no -march.  */
-      aarch64_isa_flags = cpu_isa;
-      explicit_tune_core = selected_tune ? selected_tune->ident
-					  : selected_cpu->ident;
-      gcc_assert (selected_cpu);
       selected_arch = &all_architectures[selected_cpu->arch];
-      explicit_arch = selected_arch->arch;
+      aarch64_isa_flags = cpu_isa;
     }
-
-  /* Set the arch as well as we will need it when outputing
-     the .arch directive in assembly.  */
-  if (!selected_arch)
+  else if (selected_arch)
     {
-      gcc_assert (selected_cpu);
+      selected_cpu = &all_cores[selected_arch->ident];
+      aarch64_isa_flags = arch_isa;
+    }
+  else
+    {
+      /* No -mcpu or -march specified, so use the default CPU.  */
+      selected_cpu = &all_cores[TARGET_CPU_DEFAULT];
       selected_arch = &all_architectures[selected_cpu->arch];
+      aarch64_isa_flags = selected_cpu->flags;
     }
 
+  explicit_arch = selected_arch->arch;
   if (!selected_tune)
     selected_tune = selected_cpu;
+  explicit_tune_core = selected_tune->ident;
+
+  gcc_assert (explicit_tune_core != aarch64_none);
+  gcc_assert (explicit_arch != aarch64_no_arch);
 
   if (aarch64_enable_bti == 2)
     {
@@ -17120,15 +17082,6 @@ aarch64_override_options (void)
   if (aarch64_ra_sign_scope != AARCH64_FUNCTION_NONE && TARGET_ILP32)
     sorry ("return address signing is only supported for %<-mabi=lp64%>");
 
-  /* Make sure we properly set up the explicit options.  */
-  if ((aarch64_cpu_string && valid_cpu)
-       || (aarch64_tune_string && valid_tune))
-    gcc_assert (explicit_tune_core != aarch64_none);
-
-  if ((aarch64_cpu_string && valid_cpu)
-       || (aarch64_arch_string && valid_arch))
-    gcc_assert (explicit_arch != aarch64_no_arch);
-
   /* The pass to insert speculation tracking runs before
      shrink-wrapping and the latter does not know how to update the
      tracking status.  So disable it in this case.  */



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