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| author | Richard Kenner <kenner@gcc.gnu.org> | 1995-07-28 09:57:46 -0400 |
|---|---|---|
| committer | Richard Kenner <kenner@gcc.gnu.org> | 1995-07-28 09:57:46 -0400 |
| commit | 7edd39eb80b5de5db5add3fa716e09be5dc42e47 (patch) | |
| tree | 6d9bb870bd6633e92f9f2b6864d11a0933fcfa28 /gcc/unroll.c | |
| parent | 185496bb2b6bd071b15c42c681b0c3d60390bce0 (diff) | |
| download | gcc-7edd39eb80b5de5db5add3fa716e09be5dc42e47.zip gcc-7edd39eb80b5de5db5add3fa716e09be5dc42e47.tar.gz gcc-7edd39eb80b5de5db5add3fa716e09be5dc42e47.tar.bz2 | |
(unroll_loop): When preconditioning...
(unroll_loop): When preconditioning, output code to execute loop once
if initial value is greater than or equal to final value.
From-SVN: r10188
Diffstat (limited to 'gcc/unroll.c')
| -rw-r--r-- | gcc/unroll.c | 44 |
1 files changed, 37 insertions, 7 deletions
diff --git a/gcc/unroll.c b/gcc/unroll.c index 4bc72ae..083f0ab 100644 --- a/gcc/unroll.c +++ b/gcc/unroll.c @@ -853,6 +853,19 @@ unroll_loop (loop_end, insn_count, loop_start, end_insert_before, for (i = 0; i < unroll_number; i++) labels[i] = gen_label_rtx (); + /* Check for the case where the initial value is greater than or equal + to the final value. In that case, we want to execute exactly + one loop iteration. The code below will fail for this case. */ + + emit_cmp_insn (initial_value, final_value, neg_inc ? LE : GE, + NULL_RTX, mode, 0, 0); + if (neg_inc) + emit_jump_insn (gen_ble (labels[1])); + else + emit_jump_insn (gen_bge (labels[1])); + JUMP_LABEL (get_last_insn ()) = labels[1]; + LABEL_NUSES (labels[1])++; + /* Assuming the unroll_number is 4, and the increment is 2, then for a negative increment: for a positive increment: diff = 0,1 precond 0 diff = 0,7 precond 0 @@ -869,18 +882,28 @@ unroll_loop (loop_end, insn_count, loop_start, end_insert_before, for (i = 0; i < unroll_number - 1; i++) { int cmp_const; + enum rtx_code cmp_code; /* For negative increments, must invert the constant compared against, except when comparing against zero. */ if (i == 0) - cmp_const = 0; + { + cmp_const = 0; + cmp_code = EQ; + } else if (neg_inc) - cmp_const = unroll_number - i; + { + cmp_const = unroll_number - i; + cmp_code = GE; + } else - cmp_const = i; + { + cmp_const = i; + cmp_code = LE; + } emit_cmp_insn (diff, GEN_INT (abs_inc * cmp_const), - EQ, NULL_RTX, mode, 0, 0); + cmp_code, NULL_RTX, mode, 0, 0); if (i == 0) emit_jump_insn (gen_beq (labels[i])); @@ -904,13 +927,20 @@ unroll_loop (loop_end, insn_count, loop_start, end_insert_before, if (abs_inc != 1) { int cmp_const; + enum rtx_code cmp_code; if (neg_inc) - cmp_const = abs_inc - 1; + { + cmp_const = abs_inc - 1; + cmp_code = LE; + } else - cmp_const = abs_inc * (unroll_number - 1) + 1; + { + cmp_const = abs_inc * (unroll_number - 1) + 1; + cmp_code = GE; + } - emit_cmp_insn (diff, GEN_INT (cmp_const), EQ, NULL_RTX, + emit_cmp_insn (diff, GEN_INT (cmp_const), cmp_code, NULL_RTX, mode, 0, 0); if (neg_inc) |