https://gcc.gnu.org/g:c8c3988ef66c112defe86dcd23e6679d39814587
commit r17-2598-gc8c3988ef66c112defe86dcd23e6679d39814587 Author: Takayuki 'January June' Suwa <[email protected]> Date: Sat Jul 18 05:37:13 2026 +0900 xtensa: Define LOCAL_REGNO() macro When the Windowed Register Option (TARGET_WINDOWED_ABI) is enabled, and this macro is not defined, "phantom" DF livenesses occurs in the function epilogue, which can hinder certain optimizations. Indeed, in the following example, the low-overhead loop optimization is rejected because the epilogue BB, which succeeds the target loop BB, is incorrectly identified as using the loop iterator. /* example */ void test(char *q, const char *p, unsigned int n) { do *q = *p, ++q, ++p; while (n-- != 1); } ;; before (-mabi=windowed ; TARGET_LOOPS) test: entry sp, 32 movi.n a8, 0 .L2: add.n a9, a3, a8 l8ui a10, a9, 0 add.n a9, a2, a8 s8i a10, a9, 0 addi.n a8, a8, 1 addi.n a4, a4, -1 bnez.n a4, .L2 ;; incorrectly identified as using A4 ;; in the epilogue. retw.n This patch fixes the above issue by properly defining the relevant macro. ;; after (-mabi=windowed ; TARGET_LOOPS) test: entry sp, 32 movi.n a8, 0 loop a4, .L2_LEND .L2: add.n a9, a3, a8 l8ui a10, a9, 0 add.n a9, a2, a8 s8i a10, a9, 0 addi.n a8, a8, 1 .L2_LEND: retw.n gcc/ChangeLog: * config/xtensa/xtensa.h (LOCAL_REGNO): New macro definition. Diff: --- gcc/config/xtensa/xtensa.h | 3 +++ 1 file changed, 3 insertions(+) diff --git a/gcc/config/xtensa/xtensa.h b/gcc/config/xtensa/xtensa.h index 3b33d69bf210..00bb9e06e2e9 100644 --- a/gcc/config/xtensa/xtensa.h +++ b/gcc/config/xtensa/xtensa.h @@ -344,6 +344,9 @@ along with GCC; see the file COPYING3. If not see ((unsigned) ((IN) - GP_REG_FIRST) < WINDOW_SIZE)) ? \ (IN) + WINDOW_SIZE : (IN)) : (IN)) +#define LOCAL_REGNO(REGNO) \ + (TARGET_WINDOWED_ABI && GP_REG_P (REGNO) \ + && ((unsigned) ((REGNO) - GP_REG_FIRST) < WINDOW_SIZE)) /* Define the classes of registers for register constraints in the machine description. */
