AArch64: Add support for --with-tune

Add support for --with-tune. Like --with-cpu and --with-arch, the argument is
validated and transformed into a -mtune option to be processed like any other
command-line option.  --with-tune has no effect if a -mcpu or -mtune option
is used. The validating code didn't allow --with-cpu=native, so explicitly
allow that.

Co-authored-by:  Delia Burduv  <delia.burduv@arm.com>

Bootstrap OK, regress pass, OK to commit?

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

gcc/
	* config.gcc (aarch64*-*-*): Add --with-tune. Support --with-cpu=native.
	* config/aarch64/aarch64.h (OPTION_DEFAULT_SPECS): Add --with-tune.

gcc/testsuite/
	* lib/target-supports.exp (check_effective_target_tune_cortex_a76): New
	effective target test.
	* gcc.target/aarch64/with-tune-config.c: New test.
	* gcc.target/aarch64/with-tune-march.c: Likewise.
	* gcc.target/aarch64/with-tune-mcpu.c: Likewise.
	* gcc.target/aarch64/with-tune-mtune.c: Likewise.

7 files changed, 54 insertions, 6 deletions

diff --git a/gcc/config.gcc b/gcc/config.gcc
index 3650b46..50c10dc 100644
--- a/gcc/config.gcc
+++ b/gcc/config.gcc
@@ -4157,6 +4157,12 @@ case "${target}" in
 				  sed -e 's/,.*$//'`
 			  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
+			    exit 1
+			  fi
+
 			  # Use the pre-processor to strip flatten the options.
 			  # This makes the format less rigid than if we use
 			  # grep and sed directly here.
@@ -4214,8 +4220,13 @@ case "${target}" in
 			  fi
 			  true
 			else
-			  echo "Unknown $which used in --with-$which=$val" 1>&2
-			  exit 1
+			  # Allow --with-$which=native.
+			  if [ "$val" = native ]; then
+			    true
+			  else
+			    echo "Unknown $which used in --with-$which=$val" 1>&2
+			    exit 1
+			  fi
 			fi
 		done
 		;;
diff --git a/gcc/config/aarch64/aarch64.h b/gcc/config/aarch64/aarch64.h
index 6c145cb..74bb3b5 100644
--- a/gcc/config/aarch64/aarch64.h
+++ b/gcc/config/aarch64/aarch64.h
@@ -1219,12 +1219,14 @@ extern enum aarch64_code_model aarch64_cmodel;
 #define ENDIAN_LANE_N(NUNITS, N) \
   (BYTES_BIG_ENDIAN ? NUNITS - 1 - N : N)
 
-/* Support for a configure-time default CPU, etc.  We currently support
-   --with-arch and --with-cpu.  Both are ignored if either is specified
-   explicitly on the command line at run time.  */
+/* Support for configure-time --with-arch, --with-cpu and --with-tune.
+   --with-arch and --with-cpu are ignored if either -mcpu or -march is used.
+   --with-tune is ignored if either -mtune or -mcpu is used (but is not
+   affected by -march).  */
 #define OPTION_DEFAULT_SPECS				\
   {"arch", "%{!march=*:%{!mcpu=*:-march=%(VALUE)}}" },	\
-  {"cpu",  "%{!march=*:%{!mcpu=*:-mcpu=%(VALUE)}}" },
+  {"cpu",  "%{!march=*:%{!mcpu=*:-mcpu=%(VALUE)}}" },   \
+  {"tune", "%{!mcpu=*:%{!mtune=*:-mtune=%(VALUE)}}"},
 
 #define MCPU_TO_MARCH_SPEC \
    " %{mcpu=*:-march=%:rewrite_mcpu(%{mcpu=*:%*})}"
diff --git a/gcc/testsuite/gcc.target/aarch64/with-tune-config.c b/gcc/testsuite/gcc.target/aarch64/with-tune-config.c
new file mode 100644
index 0000000..0940e9e
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/with-tune-config.c
@@ -0,0 +1,7 @@
+/* { dg-do compile { target { tune_cortex_a76 } } } */
+/* { dg-additional-options " -dA " } */
+
+void foo ()
+{}
+
+/* { dg-final { scan-assembler "//.tune cortex-a76" } } */
diff --git a/gcc/testsuite/gcc.target/aarch64/with-tune-march.c b/gcc/testsuite/gcc.target/aarch64/with-tune-march.c
new file mode 100644
index 0000000..61039ad
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/with-tune-march.c
@@ -0,0 +1,8 @@
+/* { dg-do compile { target { tune_cortex_a76 } } } */
+/* { dg-additional-options " -dA -march=armv8.6-a " } */
+
+void foo ()
+{}
+
+/* { dg-final { scan-assembler "//.tune cortex-a76" } } */
+/* { dg-final { scan-assembler ".arch armv8.6-a" } } */
diff --git a/gcc/testsuite/gcc.target/aarch64/with-tune-mcpu.c b/gcc/testsuite/gcc.target/aarch64/with-tune-mcpu.c
new file mode 100644
index 0000000..4f8267a
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/with-tune-mcpu.c
@@ -0,0 +1,8 @@
+/* { dg-do compile { target { tune_cortex_a76 } } } */
+/* { dg-additional-options " -dA -mcpu=cortex-a73" } */
+
+void foo ()
+{}
+
+/* { dg-final { scan-assembler "//.tune cortex-a73" } } */
+/* { dg-final { scan-assembler ".arch armv8-a" } } */
diff --git a/gcc/testsuite/gcc.target/aarch64/with-tune-mtune.c b/gcc/testsuite/gcc.target/aarch64/with-tune-mtune.c
new file mode 100644
index 0000000..60f795a
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/with-tune-mtune.c
@@ -0,0 +1,7 @@
+/* { dg-do compile { target { tune_cortex_a76 } } } */
+/* { dg-additional-options " -dA -mtune=cortex-a73" } */
+
+void foo ()
+{}
+
+/* { dg-final { scan-assembler "//.tune cortex-a73" } } */
diff --git a/gcc/testsuite/lib/target-supports.exp b/gcc/testsuite/lib/target-supports.exp
index ad38b75..3c02f76 100644
--- a/gcc/testsuite/lib/target-supports.exp
+++ b/gcc/testsuite/lib/target-supports.exp
@@ -10744,6 +10744,11 @@ proc check_effective_target_msp430_large {} {
     } ""]
 }
 
+# Return 1 if GCC was configured with --with-tune=cortex-a76
+proc check_effective_target_tune_cortex_a76 { } {
+    return [check_configured_with "with-tune=cortex-a76"]
+}
+
 # Return 1 if the target has an efficient means to encode large initializers
 # in the assembly.