From 2aec5b7a12f06b0ec4c5b7969ad5eb02c19ce3ff Mon Sep 17 00:00:00 2001 From: Jim Wilson Date: Fri, 20 Jan 1995 18:23:10 -0800 Subject: [PATCH] (num_sign_bit_copies): Can handle paradoxical subreg only if LOAD_EXTEND_OP is defined to SIGN_EXTEND. From-SVN: r8787 --- gcc/combine.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/gcc/combine.c b/gcc/combine.c index d7248bf610f..3a16a70f06c 100644 --- a/gcc/combine.c +++ b/gcc/combine.c @@ -7139,14 +7139,22 @@ num_sign_bit_copies (x, mode) } #ifdef WORD_REGISTER_OPERATIONS +#ifdef LOAD_EXTEND_OP /* For paradoxical SUBREGs on machines where all register operations affect the entire register, just look inside. Note that we are passing MODE to the recursive call, so the number of sign bit copies will remain relative to that mode, not the inner mode. */ - if (GET_MODE_SIZE (GET_MODE (x)) - > GET_MODE_SIZE (GET_MODE (SUBREG_REG (x)))) + /* This works only if loads sign extend. Otherwise, if we get a + reload for the inner part, it may be loaded from the stack, and + then we lose all sign bit copies that existed before the store + to the stack. */ + + if ((GET_MODE_SIZE (GET_MODE (x)) + > GET_MODE_SIZE (GET_MODE (SUBREG_REG (x)))) + && LOAD_EXTEND_OP (GET_MODE (SUBREG_REG (x))) == SIGN_EXTEND) return num_sign_bit_copies (SUBREG_REG (x), mode); +#endif #endif break; -- 2.30.2