From: Roger Sayle Date: Sat, 22 Jul 2023 20:52:55 +0000 (+0100) Subject: i386: Don't use insvti_{high,low}part with -O0 (for compile-time). X-Git-Tag: basepoints/gcc-15~7409 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=8125b12f846b41f26e58c0fe3b218d654f65d1c8;p=thirdparty%2Fgcc.git i386: Don't use insvti_{high,low}part with -O0 (for compile-time). This patch attempts to help with PR rtl-optimization/110587, a regression of -O0 compile time for the pathological pr28071.c. My recent patch helps a bit, but hasn't returned -O0 compile-time to where it was before my ix86_expand_move changes. The obvious solution/workaround is to guard these new TImode parameter passing optimizations with "&& optimize", so they don't trigger when compiling with -O0. The very minor complication is that "&& optimize" alone leads to the regression of pr110533.c, where our improved TImode parameter passing fixes a wrong-code issue with naked functions, importantly, when compiling with -O0. This should explain the one line fix below "&& (optimize || ix86_function_naked (cfun))". I've an additional fix/tweak or two for this compile-time issue, but this change eliminates the part of the regression that I've caused. 2023-07-22 Roger Sayle gcc/ChangeLog * config/i386/i386-expand.cc (ix86_expand_move): Disable the 64-bit insertions into TImode optimizations with -O0, unless the function has the "naked" attribute (for PR target/110533). --- diff --git a/gcc/config/i386/i386-expand.cc b/gcc/config/i386/i386-expand.cc index a5c000f366d9..042190982557 100644 --- a/gcc/config/i386/i386-expand.cc +++ b/gcc/config/i386/i386-expand.cc @@ -544,6 +544,8 @@ ix86_expand_move (machine_mode mode, rtx operands[]) /* Special case inserting 64-bit values into a TImode register. */ if (TARGET_64BIT + /* Disable for -O0 (see PR110587) unless naked (PR110533). */ + && (optimize || ix86_function_naked (current_function_decl)) && (mode == DImode || mode == DFmode) && SUBREG_P (op0) && GET_MODE (SUBREG_REG (op0)) == TImode