[PATCH] rs6000: avoid peeking eof after __vector

[Jiufu Guo <guojiufu@linux.ibm.com>]

Hi!

This patch is based on:
https://gcc.gnu.org/pipermail/gcc-patches/2022-March/592102.html
And update the 'function comment' to make it consistent with code.

There is a rare corner case: where vector is followed only by one
valid identifer and the ";" which is near the end of the file.

Like the case in PR101168:
using vdbl =  __vector double;
#define BREAK 1

For this case, "vector double" is followed by CPP_SEMICOLON and then
EOF.  There is no more tokens need to check for this case.

This patch pass bootstrap and regtest on ppc64 and ppc64le.


BR,
Jiufu


	PR preprocessor/101168

gcc/ChangeLog:

	* config/rs6000/rs6000-c.cc (rs6000_macro_to_expand):
	Avoid empty identifier.

gcc/testsuite/ChangeLog:

	* g++.target/powerpc/pr101168.C: New test.


---
 gcc/config/rs6000/rs6000-c.cc               | 9 +++++----
 gcc/testsuite/g++.target/powerpc/pr101168.C | 6 ++++++
 2 files changed, 11 insertions(+), 4 deletions(-)
 create mode 100644 gcc/testsuite/g++.target/powerpc/pr101168.C

diff --git a/gcc/config/rs6000/rs6000-c.cc b/gcc/config/rs6000/rs6000-c.cc
index 84bb98f94fb..9c8cbd7a66e 100644
--- a/gcc/config/rs6000/rs6000-c.cc
+++ b/gcc/config/rs6000/rs6000-c.cc
@@ -178,9 +178,8 @@ rid_int128(void)
   return RID_MAX + 1;
 }
 
-/* Called to decide whether a conditional macro should be expanded.
-   Since we have exactly one such macro (i.e, 'vector'), we do not
-   need to examine the 'tok' parameter.  */
+/* Called to decide whether a conditional macro should be expanded
+   by peeking two or more tokens(_bool/_pixel/int/long/double/...).  */
 
 static cpp_hashnode *
 rs6000_macro_to_expand (cpp_reader *pfile, const cpp_token *tok)
@@ -282,7 +281,9 @@ rs6000_macro_to_expand (cpp_reader *pfile, const cpp_token *tok)
 		expand_bool_pixel = __pixel_keyword;
 	      else if (ident == C_CPP_HASHNODE (__bool_keyword))
 		expand_bool_pixel = __bool_keyword;
-	      else
+
+	      /* If there are more tokens to check.  */
+	      else if (ident)
 		{
 		  /* Try two tokens down, too.  */
 		  do
diff --git a/gcc/testsuite/g++.target/powerpc/pr101168.C b/gcc/testsuite/g++.target/powerpc/pr101168.C
new file mode 100644
index 00000000000..284e77fdc88
--- /dev/null
+++ b/gcc/testsuite/g++.target/powerpc/pr101168.C
@@ -0,0 +1,6 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target powerpc_altivec_ok } */
+/* { dg-options "-maltivec" } */
+
+using vdbl =  __vector double;
+#define BREAK 1
-- 
2.25.1