From 8b99780039c7735aae73df6e19a301bf50b53ca0 Mon Sep 17 00:00:00 2001 From: law Date: Fri, 14 Feb 2014 20:26:31 +0000 Subject: PR rtl-optimization/60131 * ree.c (get_extended_src_reg): New function. (combine_reaching_defs): Use it rather than assuming location of REG. (find_and_remove_re): Verify first operand of extension is a REG before adding the insns to the copy list. PR rtl-optimization/60131 * g++.dg/torture/pr60131.C: New test. git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@207792 138bc75d-0d04-0410-961f-82ee72b054a4 --- gcc/ree.c | 37 ++++++++++++++++++++++++++++++------- 1 file changed, 30 insertions(+), 7 deletions(-) (limited to 'gcc/ree.c') diff --git a/gcc/ree.c b/gcc/ree.c index 421eb6cb89b..fcde9a0f399 100644 --- a/gcc/ree.c +++ b/gcc/ree.c @@ -670,6 +670,18 @@ merge_def_and_ext (ext_cand *cand, rtx def_insn, ext_state *state) return false; } +/* Given SRC, which should be one or more extensions of a REG, strip + away the extensions and return the REG. */ + +static inline rtx +get_extended_src_reg (rtx src) +{ + while (GET_CODE (src) == SIGN_EXTEND || GET_CODE (src) == ZERO_EXTEND) + src = XEXP (src, 0); + gcc_assert (REG_P (src)); + return src; +} + /* This function goes through all reaching defs of the source of the candidate for elimination (CAND) and tries to combine the extension with the definition instruction. The changes @@ -698,17 +710,23 @@ combine_reaching_defs (ext_cand *cand, const_rtx set_pat, ext_state *state) /* If the destination operand of the extension is a different register than the source operand, then additional restrictions - are needed. */ - if ((REGNO (SET_DEST (PATTERN (cand->insn))) - != REGNO (XEXP (SET_SRC (PATTERN (cand->insn)), 0)))) + are needed. Note we have to handle cases where we have nested + extensions in the source operand. */ + if (REGNO (SET_DEST (PATTERN (cand->insn))) + != REGNO (get_extended_src_reg (SET_SRC (PATTERN (cand->insn))))) { /* In theory we could handle more than one reaching def, it just makes the code to update the insn stream more complex. */ if (state->defs_list.length () != 1) return false; - /* We require the candidate not already be modified. This may - be overly conservative. */ + /* We require the candidate not already be modified. It may, + for example have been changed from a (sign_extend (reg)) + into (zero_extend (sign_extend (reg)). + + Handling that case shouldn't be terribly difficult, but the code + here and the code to emit copies would need auditing. Until + we see a need, this is the safe thing to do. */ if (state->modified[INSN_UID (cand->insn)].kind != EXT_MODIFIED_NONE) return false; @@ -999,8 +1017,13 @@ find_and_remove_re (void) if (dump_file) fprintf (dump_file, "Eliminated the extension.\n"); num_realized++; - if (REGNO (SET_DEST (PATTERN (curr_cand->insn))) - != REGNO (XEXP (SET_SRC (PATTERN (curr_cand->insn)), 0))) + /* If the RHS of the current candidate is not (extend (reg)), then + we do not allow the optimization of extensions where + the source and destination registers do not match. Thus + checking REG_P here is correct. */ + if (REG_P (XEXP (SET_SRC (PATTERN (curr_cand->insn)), 0)) + && (REGNO (SET_DEST (PATTERN (curr_cand->insn))) + != REGNO (XEXP (SET_SRC (PATTERN (curr_cand->insn)), 0)))) { reinsn_copy_list.safe_push (curr_cand->insn); reinsn_copy_list.safe_push (state.defs_list[0]); -- cgit v1.2.1