STAGE1_CFLAGS can be used to accelerate the just-built stage1 compiler
which especially improves its performance on some of the large generated
files during bootstrap. It defaults to nothing (i.e. -O0).
The downside is that if the native compiler is buggy, there's a greater
risk of a failed bootstrap. Those with a modern native compiler, ideally
a recent version of GCC, should be able to use -O1 or -O2 without issue
to get a faster build.
PR rtl-optimization/111619
* doc/install.texi (Building a native compiler): Discuss STAGE1_CFLAGS.
---
This came out of a discussion between mjw and I a little while ago when
working on the buildbots. OK?
gcc/doc/install.texi | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/gcc/doc/install.texi b/gcc/doc/install.texi
index 705440ffd330..4bd60555af9b 100644
--- a/gcc/doc/install.texi
+++ b/gcc/doc/install.texi
@@ -3017,7 +3017,11 @@ bootstrapped, you can use @code{CFLAGS_FOR_TARGET} to
modify their
compilation flags, as for non-bootstrapped target libraries.
Again, if the native compiler miscompiles the stage1 compiler, you may
need to work around this by avoiding non-working parts of the stage1
-compiler. Use @code{STAGE1_TFLAGS} to this end.
+compiler. Use @code{STAGE1_CFLAGS} and @code{STAGE1_TFLAGS} (for target
+libraries) to this end. The default value for @code{STAGE1_CFLAGS} is
+@samp{STAGE1_CFLAGS='-O0'} to increase the chances of a successful bootstrap
+with a buggy native compiler. Changing this to @code{-O1} or @code{-O2}
+can improve bootstrap times, with some greater risk of a failed bootstrap.
If you used the flag @option{--enable-languages=@dots{}} to restrict
the compilers to be built, only those you've actually enabled will be
base-commit: 00448f9b5a123b4b6b3e6f45d2fecf0a5dca66b3
--
2.47.0
