[PATCH] gcc: honour -ffile-prefix-map in ASM_MAP [PR93371]

Rasmus Villemoes rv@rasmusvillemoes.dk
Mon Aug 29 09:29:17 GMT 2022

-ffile-prefix-map is supposed to be a superset of -fmacro-prefix-map
and -fdebug-prefix-map. However, when building .S or .s files, gas is
not called with the appropriate --debug-prefix-map option when
-ffile-prefix-map is used.

While the user can specify -fdebug-prefix-map when building assembly
files via gcc, it's more ergonomic to also support -ffile-prefix-map;
especially since for .S files that could contain the __FILE__ macro,
one would then also have to specify -fmacro-prefix-map.

	PR driver/93371
	* gcc.cc (ASM_MAP): Honour -ffile-prefix-map.

I've tested that this works as expected, both by looking at how gas is
now invoked, and by running 'strings' on the generated .o file. But I
don't know how to add something to the testsuite for this.

I stumbled on this since it came up on the U-Boot mailing list:

 gcc/gcc.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/gcc/gcc.cc b/gcc/gcc.cc
index b6d562a92f0..44eafc60187 100644
--- a/gcc/gcc.cc
+++ b/gcc/gcc.cc
@@ -878,7 +878,7 @@ proper position among the other output files.  */
-#define ASM_MAP " %{fdebug-prefix-map=*:--debug-prefix-map %*}"
+#define ASM_MAP " %{ffile-prefix-map=*:--debug-prefix-map %*} %{fdebug-prefix-map=*:--debug-prefix-map %*}"
 #define ASM_MAP ""

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