gas: Pass max_bytes to TC_FRAG_INIT

ommit 3ae729d5a4f63740ed9a778960b17c2912b0bbdd
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Wed Mar 7 04:18:45 2018 -0800

    x86: Rewrite NOP generation for fill and alignment

increased MAX_MEM_FOR_RS_ALIGN_CODE to 4095 which resulted in increase
of assembler time and memory usage by 5 times for inputs with many
.p2align directives, which is typical for LTO output.  This patch passes
max_bytes to TC_FRAG_INIT so that MAX_MEM_FOR_RS_ALIGN_CODE can be set
as needed and tracked by backend it so that HANDLE_ALIGN can check the
maximum alignment for each rs_align_code frag.  Wall time to assemble
the same cc1plus.s:

before:

423.78user 0.89system 7:05.71elapsed 99%CPU

after:

102.35user 0.27system 1:42.89elapsed 99%CPU

	PR gas/24165
	* config/tc-i386.h (MAX_MEM_FOR_RS_ALIGN_CODE): Set to
	(alignment ? ((1 << alignment) - 1) : 1)
	(i386_tc_frag_data): Add max_bytes.
	(TC_FRAG_INIT): Track max_chars in max_bytes.
	(HANDLE_ALIGN): Replace MAX_MEM_FOR_RS_ALIGN_CODE with
	fragP->tc_frag_data.max_bytes.

(cherry picked from commit db22231044df03bbcb987496f3f29f0462b2e9ee)

diff --git a/gas/config/tc-i386.h b/gas/config/tc-i386.h
index f10b00df9c6a56dbb015dd5530194ab98eec3335..fcb87e83a88ec14e60abf708052604d4b260cfea 100644 (file)
--- a/gas/config/tc-i386.h
+++ b/gas/config/tc-i386.h
@@ -206,7 +206,7 @@ if ((n)                                                                     \
     goto around;                                                       \
   }
 
-#define MAX_MEM_FOR_RS_ALIGN_CODE 4095
+#define MAX_MEM_FOR_RS_ALIGN_CODE  (alignment ? ((1 << alignment) - 1) : 1)
 
 void i386_print_statistics (FILE *);
 #define tc_print_statistics i386_print_statistics
@@ -251,6 +251,7 @@ struct i386_tc_frag_data
   enum processor_type isa;
   i386_cpu_flags isa_flags;
   enum processor_type tune;
+  unsigned int max_bytes;
 };
 
 /* We need to emit the right NOP pattern in .align frags.  This is
@@ -258,12 +259,14 @@ struct i386_tc_frag_data
    the isa/tune settings at the time the .align was assembled.  */
 #define TC_FRAG_TYPE struct i386_tc_frag_data
 
+/* NB: max_chars is a local variable in frag_var_init.  */
 #define TC_FRAG_INIT(FRAGP)                                    \
  do                                                            \
    {                                                           \
      (FRAGP)->tc_frag_data.isa = cpu_arch_isa;                 \
      (FRAGP)->tc_frag_data.isa_flags = cpu_arch_isa_flags;     \
      (FRAGP)->tc_frag_data.tune = cpu_arch_tune;               \
+     (FRAGP)->tc_frag_data.max_bytes = max_chars;              \
    }                                                           \
  while (0)
 
@@ -280,7 +283,8 @@ if (fragP->fr_type == rs_align_code)                                        \
     offsetT __count = (fragP->fr_next->fr_address                      \
                       - fragP->fr_address                              \
                       - fragP->fr_fix);                                \
-    if (__count > 0 && __count <= MAX_MEM_FOR_RS_ALIGN_CODE)           \
+    if (__count > 0                                                    \
+       && (unsigned int) __count <= fragP->tc_frag_data.max_bytes)     \
       md_generate_nops (fragP, fragP->fr_literal + fragP->fr_fix,      \
                        __count, 0);                                    \
   }