[gcc r10-6040] [PR93306] Short-circuit has_include

[Nathan Sidwell]

https://gcc.gnu.org/g:bf09d886a4be1031f7003073115af6cbc5575353

commit r10-6040-gbf09d886a4be1031f7003073115af6cbc5575353
Author: Nathan Sidwell <nathan@acm.org>
Date:   Fri Jan 17 05:39:47 2020 -0800

    [PR93306] Short-circuit has_include
    
    the preprocessor evaluator has a skip_eval counter, but we weren't
    checking it after parsing has_include(foo), but before looking for
    foo.  Resulting in unnecessary io for 'FALSE_COND && has_include <foo>'
    
    	PR preprocessor/93306
    	* expr.c (parse_has_include): Refactor.  Check skip_eval before
    	looking.

Diff:
---
 libcpp/ChangeLog |  6 ++++++
 libcpp/expr.c    | 34 ++++++++++++----------------------
 2 files changed, 18 insertions(+), 22 deletions(-)

diff --git a/libcpp/ChangeLog b/libcpp/ChangeLog
index fc22011..3249b93 100644
--- a/libcpp/ChangeLog
+++ b/libcpp/ChangeLog
@@ -1,3 +1,9 @@
+2020-01-17  Nathan Sidwell  <nathan@acm.org>
+
+	PR preprocessor/93306
+	* expr.c (parse_has_include): Refactor.  Check skip_eval before
+	looking.
+
 2020-01-10  David Malcolm  <dmalcolm@redhat.com>
 
 	* include/line-map.h (class diagnostic_path): New forward decl.
diff --git a/libcpp/expr.c b/libcpp/expr.c
index 1078c07..317faf5 100644
--- a/libcpp/expr.c
+++ b/libcpp/expr.c
@@ -2195,11 +2195,6 @@ static cpp_num
 parse_has_include (cpp_reader *pfile, enum include_type type)
 {
   cpp_num result;
-  bool paren = false;
-  cpp_hashnode *node = 0;
-  const cpp_token *token;
-  bool bracket = false;
-  char *fname = 0;
 
   result.unsignedp = false;
   result.high = 0;
@@ -2208,39 +2203,34 @@ parse_has_include (cpp_reader *pfile, enum include_type type)
 
   pfile->state.in__has_include__++;
 
-  token = cpp_get_token (pfile);
-  if (token->type == CPP_OPEN_PAREN)
-    {
-      paren = true;
-      token = cpp_get_token (pfile);
-    }
+  const cpp_token *token = cpp_get_token (pfile);
+  bool paren = token->type == CPP_OPEN_PAREN;
+  if (paren)
+    token = cpp_get_token (pfile);
 
+  bool bracket = token->type != CPP_STRING;
+  cpp_hashnode *node = NULL;
+  char *fname = NULL;
   if (token->type == CPP_STRING || token->type == CPP_HEADER_NAME)
     {
-      if (token->type == CPP_HEADER_NAME)
-	bracket = true;
       fname = XNEWVEC (char, token->val.str.len - 1);
       memcpy (fname, token->val.str.text + 1, token->val.str.len - 2);
       fname[token->val.str.len - 2] = '\0';
       node = token->val.node.node;
     }
   else if (token->type == CPP_LESS)
-    {
-      bracket = true;
-      fname = _cpp_bracket_include (pfile);
-    }
+    fname = _cpp_bracket_include (pfile);
   else
     cpp_error (pfile, CPP_DL_ERROR,
 	       "operator \"__has_include__\" requires a header string");
 
   if (fname)
     {
-      int angle_brackets = (bracket ? 1 : 0);
-
-      if (_cpp_has_header (pfile, fname, angle_brackets, type))
+      /* Do not do the lookup if we're skipping, that's unnecessary
+	 IO.  */
+      if (!pfile->state.skip_eval
+	  && _cpp_has_header (pfile, fname, bracket, type))
 	result.low = 1;
-      else
-	result.low = 0;
 
       XDELETEVEC (fname);
     }