https://gcc.gnu.org/g:cb4626dcca3c78f98ebac1485777f254583ec8bc
commit cb4626dcca3c78f98ebac1485777f254583ec8bc Author: Kishan Parmar <[email protected]> Date: Thu Jul 2 14:36:42 2026 +0530 rs6000: Fix %Y print modifier to use VSX numbering for VSX registers [PR125549] The %Y print operand modifier unconditionally prints reg_names[REGNO (x) + 2], i.e. it adds 2 to the register's hardware register number. Some instruction patterns for a future Power processor print one operand with '%x', which forces that operand to be printed and follow (and allocated) using VSX register numbering. A second, related operand in the same pattern is printed with %Y, which is meant to give the next register in sequence relative to the first. The %Y operand modifier always added 2 to the hardware register number without first converting to VSX register numbering. Reason being result did not match the numbering used by '%x' in the same instruction whenever an Altivec register was allocated, causing later code to reference the wrong physical registers. Fix %Y so that, for VSX-eligible registers, it converts to VSX register numbering before adding 2, matching '%x'. Non-VSX registers are unaffected. 2026-07-02 Kishan Parmar <[email protected]> gcc/ChangeLog: PR target/125549 * config/rs6000/rs6000.cc (print_operand) <case 'Y'>: Convert VSX-eligible registers to VSX numbering before adding 2. Diff: --- gcc/config/rs6000/rs6000.cc | 25 ++++++++++++++++++++++++- 1 file changed, 24 insertions(+), 1 deletion(-) diff --git a/gcc/config/rs6000/rs6000.cc b/gcc/config/rs6000/rs6000.cc index eff6e44c75cf..db54720f61c8 100644 --- a/gcc/config/rs6000/rs6000.cc +++ b/gcc/config/rs6000/rs6000.cc @@ -14552,7 +14552,30 @@ print_operand (FILE *file, rtx x, int code) case 'Y': /* Like 'L', for third word of TImode/PTImode */ if (REG_P (x)) - fputs (reg_names[REGNO (x) + 2], file); + { + /* Check if this is a register being used in a VSX context. + If so, convert to VSX numbering and add 2. */ + if (VSX_REGNO_P (REGNO (x))) + { + int reg = REGNO (x); + int vsx_reg = (FP_REGNO_P (reg) + ? reg - 32 + : reg - FIRST_ALTIVEC_REGNO + 32); + vsx_reg += 2; + +#ifdef TARGET_REGNAMES + if (TARGET_REGNAMES) + fprintf (file, "%%vs%d", vsx_reg); + else +#endif + fprintf (file, "%d", vsx_reg); + } + else + { + /* Non-VSX register: use original behavior (add 2 to hardware reg) */ + fputs (reg_names[REGNO (x) + 2], file); + } + } else if (MEM_P (x)) { machine_mode mode = GET_MODE (x);
