Add source information to -fverbose-asm

gcc/ChangeLog:
	* doc/invoke.texi (fverbose-asm): Note that source code lines
	are emitted, and provide an example.
	* final.c (asm_show_source): New function.
	(final_scan_insn): Call asm_show_source.

From-SVN: r239604

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index c268e0001ababfc9f3de306fa86e3299fd6a4e01..65efe1e5513d8d771e36bf30de12ad6661dab043 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2016-08-18  David Malcolm  <dmalcolm@redhat.com>
+
+       * doc/invoke.texi (fverbose-asm): Note that source code lines
+       are emitted, and provide an example.
+       * final.c (asm_show_source): New function.
+       (final_scan_insn): Call asm_show_source.
+
 2016-08-18  David Malcolm  <dmalcolm@redhat.com>
 
        * diagnostic-show-locus.c (colorizer::colorizer): Replace diagnostic

diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index d04be6fd4c86cd8299ac5b7c29d0a3c075295406..1f0450135490325f717da947eaefb86560bf07dc 100644 (file)
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -11426,6 +11426,89 @@ debugging the compiler itself).
 extra information to be omitted and is useful when comparing two assembler
 files.
 
+The added comments include:
+
+@itemize @bullet
+
+@item
+information on the compiler version and command-line options,
+
+@item
+the source code lines associated with the assembly instructions,
+in the form FILENAME:LINENUMBER:CONTENT OF LINE,
+
+@item
+hints on which high-level expressions correspond to
+the various assembly instruction operands.
+
+@end itemize
+
+For example, given this C source file:
+
+@smallexample
+int test (int n)
+@{
+  int i;
+  int total = 0;
+
+  for (i = 0; i < n; i++)
+    total += i * i;
+
+  return total;
+@}
+@end smallexample
+
+compiling to (x86_64) assembly via @option{-S} and emitting the result
+direct to stdout via @option{-o} @option{-}
+
+@smallexample
+gcc -S test.c -fverbose-asm -Os -o -
+@end smallexample
+
+gives output similar to this:
+
+@smallexample
+       .file   "test.c"
+# GNU C11 (GCC) version 7.0.0 20160809 (experimental) (x86_64-pc-linux-gnu)
+  [...snip...]
+# options passed:
+  [...snip...]
+
+       .text
+       .globl  test
+       .type   test, @@function
+test:
+.LFB0:
+       .cfi_startproc
+# test.c:4:   int total = 0;
+       xorl    %eax, %eax      # <retval>
+# test.c:6:   for (i = 0; i < n; i++)
+       xorl    %edx, %edx      # i
+.L2:
+# test.c:6:   for (i = 0; i < n; i++)
+       cmpl    %edi, %edx      # n, i
+       jge     .L5     #,
+# test.c:7:     total += i * i;
+       movl    %edx, %ecx      # i, tmp92
+       imull   %edx, %ecx      # i, tmp92
+# test.c:6:   for (i = 0; i < n; i++)
+       incl    %edx    # i
+# test.c:7:     total += i * i;
+       addl    %ecx, %eax      # tmp92, <retval>
+       jmp     .L2     #
+.L5:
+# test.c:10: @}
+       ret
+       .cfi_endproc
+.LFE0:
+       .size   test, .-test
+       .ident  "GCC: (GNU) 7.0.0 20160809 (experimental)"
+       .section        .note.GNU-stack,"",@@progbits
+@end smallexample
+
+The comments are intended for humans rather than machines and hence the
+precise format of the comments is subject to change.
+
 @item -frecord-gcc-switches
 @opindex frecord-gcc-switches
 This switch causes the command line used to invoke the

diff --git a/gcc/final.c b/gcc/final.c
index 5b04311218e29432dd29bebec06438a92abbb066..eccc3d817101936b84c62504ceda0bc1dec8eeb5 100644 (file)
--- a/gcc/final.c
+++ b/gcc/final.c
@@ -2140,6 +2140,26 @@ call_from_call_insn (rtx_call_insn *insn)
   return x;
 }
 
+/* Print a comment into the asm showing FILENAME, LINENUM, and the
+   corresponding source line, if available.  */
+
+static void
+asm_show_source (const char *filename, int linenum)
+{
+  if (!filename)
+    return;
+
+  int line_size;
+  const char *line = location_get_source_line (filename, linenum, &line_size);
+  if (!line)
+    return;
+
+  fprintf (asm_out_file, "%s %s:%i: ", ASM_COMMENT_START, filename, linenum);
+  /* "line" is not 0-terminated, so we must use line_size.  */
+  fwrite (line, 1, line_size, asm_out_file);
+  fputc ('\n', asm_out_file);
+}
+
 /* The final scan for one insn, INSN.
    Args are same as in `final', except that INSN
    is the insn being scanned.
@@ -2563,8 +2583,12 @@ final_scan_insn (rtx_insn *insn, FILE *file, int optimize_p ATTRIBUTE_UNUSED,
           note in a row.  */
        if (!DECL_IGNORED_P (current_function_decl)
            && notice_source_line (insn, &is_stmt))
-         (*debug_hooks->source_line) (last_linenum, last_filename,
-                                      last_discriminator, is_stmt);
+         {
+           if (flag_verbose_asm)
+             asm_show_source (last_filename, last_linenum);
+           (*debug_hooks->source_line) (last_linenum, last_filename,
+                                        last_discriminator, is_stmt);
+         }
 
        if (GET_CODE (body) == PARALLEL
            && GET_CODE (XVECEXP (body, 0, 0)) == ASM_INPUT)

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 7da55951e9a435a56a4b250ffa688053f0cf2630..dd893ca414ab79f284011f748c765a5067b628ab 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2016-08-18  David Malcolm  <dmalcolm@redhat.com>
+
+       * gcc.dg/verbose-asm-2.c: New test case.
+
 2016-08-18  David Malcolm  <dmalcolm@redhat.com>
 
        * gcc.dg/plugin/diagnostic_plugin_test_show_locus.c

diff --git a/gcc/testsuite/gcc.dg/verbose-asm-2.c b/gcc/testsuite/gcc.dg/verbose-asm-2.c
new file mode 100644 (file)
index 0000000..747bff1
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/verbose-asm-2.c
@@ -0,0 +1,15 @@
+/* Ensure that the -fverbose-asm leads to source code information in the generated asm.  */
+/* { dg-options "-fverbose-asm" } */
+
+int test (int n)
+{
+  int i;
+  int total = 0;
+
+  for (i = 0; i < n; i++)
+    total += i * i;
+
+  return total;
+}
+
+/* { dg-final { scan-assembler "total = 0" } } */