On Mon, Mar 14, 2016 at 01:00:39PM -0600, Jeff Law wrote: > Right. Tolerant as in not crash.
So can someone please approve my ira.c:indirect_jump_optimize patch? I'm not quite audacious enough to claim it is obvious. The original is at https://gcc.gnu.org/ml/gcc-patches/2016-03/msg00720.html, reposted here with some additional comments. Bootstrapped and regression tested powerpc64le-linux and x86_64-linux. (In the thread I mentioned we could use DF_REF_INSN_INFO in place of !DF_REF_IS_ARTIFICAL. I believe that is true, and it saves an access to another field of df_ref, but !DF_REF_IS_ARTIFICIAL before access to DF_REF_INSN or DF_REF_INSN_UID is somewhat more prevalent in the gcc sources.) PR rtl-optimization/69195 PR rtl-optimization/47992 * ira.c (indirect_jump_optimize): Ignore artificial defs. Add comments. diff --git a/gcc/ira.c b/gcc/ira.c index 5e7a2ed..a543d90 100644 --- a/gcc/ira.c +++ b/gcc/ira.c @@ -3842,7 +3842,8 @@ update_equiv_regs (void) free (pdx_subregs); } -/* A pass over indirect jumps, converting simple cases to direct jumps. */ +/* A pass over indirect jumps, converting simple cases to direct jumps. + Combine does this optimization too, but only within a basic block. */ static void indirect_jump_optimize (void) { @@ -3862,14 +3863,23 @@ indirect_jump_optimize (void) int regno = REGNO (SET_SRC (x)); if (DF_REG_DEF_COUNT (regno) == 1) { - rtx_insn *def_insn = DF_REF_INSN (DF_REG_DEF_CHAIN (regno)); - rtx note = find_reg_note (def_insn, REG_LABEL_OPERAND, NULL_RTX); - - if (note) + df_ref def = DF_REG_DEF_CHAIN (regno); + if (!DF_REF_IS_ARTIFICIAL (def)) { - rtx lab = gen_rtx_LABEL_REF (Pmode, XEXP (note, 0)); - if (validate_replace_rtx (SET_SRC (x), lab, insn)) - rebuild_p = true; + rtx_insn *def_insn = DF_REF_INSN (def); + rtx note = find_reg_note (def_insn, REG_LABEL_OPERAND, NULL_RTX); + + if (note) + { + /* Substitute a LABEL_REF to the label given by the + note rather than using SET_SRC of DEF_INSN. + DEF_INSN might be loading the label constant from + a constant pool, which isn't what we want in a + direct branch. */ + rtx lab = gen_rtx_LABEL_REF (Pmode, XEXP (note, 0)); + if (validate_replace_rtx (SET_SRC (x), lab, insn)) + rebuild_p = true; + } } } } -- Alan Modra Australia Development Lab, IBM
