https://gcc.gnu.org/g:d04ee599f2b7bde5bcef0ea5ff09dbacab214046
commit d04ee599f2b7bde5bcef0ea5ff09dbacab214046
Author: Jeff Law <j...@ventanamicro.com>
Date: Wed May 15 17:05:24 2024 -0600
Add missing hunk in recent change.
gcc/
* config/riscv/riscv-string.cc: Add missing hunk from last change.
(cherry picked from commit d7e6fe0f72ad41b8361f927d2796dbc275347297)
Diff:
---
gcc/config/riscv/riscv-string.cc | 177 +++++++++++++++++++++++++++++++++++++++
1 file changed, 177 insertions(+)
diff --git a/gcc/config/riscv/riscv-string.cc b/gcc/config/riscv/riscv-string.cc
index cbb9724d230..83e7afbd693 100644
--- a/gcc/config/riscv/riscv-string.cc
+++ b/gcc/config/riscv/riscv-string.cc
@@ -627,6 +627,183 @@ riscv_expand_strlen (rtx result, rtx src, rtx
search_char, rtx align)
return false;
}
+/* Generate the sequence of load and compares for memcmp using Zbb.
+
+ RESULT is the register where the return value of memcmp will be stored.
+ The source pointers are SRC1 and SRC2 (NBYTES bytes to compare).
+ DATA1 and DATA2 are registers where the data chunks will be stored.
+ DIFF_LABEL is the location of the code that calculates the return value.
+ FINAL_LABEL is the location of the code that comes after the calculation
+ of the return value. */
+
+static void
+emit_memcmp_scalar_load_and_compare (rtx result, rtx src1, rtx src2,
+ unsigned HOST_WIDE_INT nbytes,
+ rtx data1, rtx data2,
+ rtx diff_label, rtx final_label)
+{
+ const unsigned HOST_WIDE_INT xlen = GET_MODE_SIZE (Xmode);
+ unsigned HOST_WIDE_INT offset = 0;
+
+ while (nbytes > 0)
+ {
+ unsigned HOST_WIDE_INT cmp_bytes = xlen < nbytes ? xlen : nbytes;
+ machine_mode load_mode;
+
+ /* Special cases to avoid masking of trailing bytes. */
+ if (cmp_bytes == 1)
+ load_mode = QImode;
+ else if (cmp_bytes == 2)
+ load_mode = HImode;
+ else if (cmp_bytes == 4)
+ load_mode = SImode;
+ else
+ load_mode = Xmode;
+
+ rtx addr1 = adjust_address (src1, load_mode, offset);
+ do_load (load_mode, data1, addr1);
+ rtx addr2 = adjust_address (src2, load_mode, offset);
+ do_load (load_mode, data2, addr2);
+
+ /* Fast-path for a single byte. */
+ if (cmp_bytes == 1)
+ {
+ rtx tmp = gen_reg_rtx (Xmode);
+ do_sub3 (tmp, data1, data2);
+ emit_insn (gen_movsi (result, gen_lowpart (SImode, tmp)));
+ emit_jump_insn (gen_jump (final_label));
+ emit_barrier (); /* No fall-through. */
+ return;
+ }
+
+ /* Shift off trailing bytes in words if needed. */
+ unsigned int load_bytes = GET_MODE_SIZE (load_mode).to_constant ();
+ if (cmp_bytes < load_bytes)
+ {
+ int shamt = (load_bytes - cmp_bytes) * BITS_PER_UNIT;
+ do_ashl3 (data1, data1, GEN_INT (shamt));
+ do_ashl3 (data2, data2, GEN_INT (shamt));
+ }
+
+ /* Break out if data1 != data2 */
+ rtx cond = gen_rtx_NE (VOIDmode, data1, data2);
+ emit_unlikely_jump_insn (gen_cbranch4 (Pmode, cond, data1,
+ data2, diff_label));
+ /* Fall-through on equality. */
+
+ offset += cmp_bytes;
+ nbytes -= cmp_bytes;
+ }
+}
+
+/* memcmp result calculation.
+
+ RESULT is the register where the return value will be stored.
+ The two data chunks are in DATA1 and DATA2. */
+
+static void
+emit_memcmp_scalar_result_calculation (rtx result, rtx data1, rtx data2)
+{
+ /* Get bytes in big-endian order and compare as words. */
+ do_bswap2 (data1, data1);
+ do_bswap2 (data2, data2);
+ /* Synthesize (data1 >= data2) ? 1 : -1 in a branchless sequence. */
+ rtx tmp = gen_reg_rtx (Xmode);
+ emit_insn (gen_slt_3 (LTU, Xmode, Xmode, tmp, data1, data2));
+ do_neg2 (tmp, tmp);
+ do_ior3 (tmp, tmp, const1_rtx);
+ emit_insn (gen_movsi (result, gen_lowpart (SImode, tmp)));
+}
+
+/* Expand memcmp using scalar instructions (incl. Zbb).
+
+ RESULT is the register where the return value will be stored.
+ The source pointers are SRC1 and SRC2 (NBYTES bytes to compare). */
+
+static bool
+riscv_expand_block_compare_scalar (rtx result, rtx src1, rtx src2, rtx nbytes)
+{
+ const unsigned HOST_WIDE_INT xlen = GET_MODE_SIZE (Xmode);
+
+ if (optimize_function_for_size_p (cfun))
+ return false;
+
+ /* We don't support big endian. */
+ if (BYTES_BIG_ENDIAN)
+ return false;
+
+ if (!CONST_INT_P (nbytes))
+ return false;
+
+ /* We need the rev (bswap) instruction. */
+ if (!TARGET_ZBB)
+ return false;
+
+ unsigned HOST_WIDE_INT length = UINTVAL (nbytes);
+
+ /* Limit to 12-bits (maximum load-offset). */
+ if (length > IMM_REACH)
+ length = IMM_REACH;
+
+ /* We need xlen-aligned memory. */
+ unsigned HOST_WIDE_INT align = MIN (MEM_ALIGN (src1), MEM_ALIGN (src2));
+ if (align < (xlen * BITS_PER_UNIT))
+ return false;
+
+ if (length > RISCV_MAX_MOVE_BYTES_STRAIGHT)
+ return false;
+
+ /* Overall structure of emitted code:
+ Load-and-compare:
+ - Load data1 and data2
+ - Compare strings and either:
+ - Fall-through on equality
+ - Jump to end_label if data1 != data2
+ // Fall-through
+ Set result to 0 and jump to final_label
+ diff_label:
+ Calculate result value with the use of data1 and data2
+ Jump to final_label
+ final_label:
+ // Nothing. */
+
+ rtx data1 = gen_reg_rtx (Xmode);
+ rtx data2 = gen_reg_rtx (Xmode);
+ rtx diff_label = gen_label_rtx ();
+ rtx final_label = gen_label_rtx ();
+
+ /* Generate a sequence of zbb instructions to compare out
+ to the length specified. */
+ emit_memcmp_scalar_load_and_compare (result, src1, src2, length,
+ data1, data2,
+ diff_label, final_label);
+
+ emit_insn (gen_rtx_SET (result, gen_rtx_CONST_INT (SImode, 0)));
+ emit_jump_insn (gen_jump (final_label));
+ emit_barrier (); /* No fall-through. */
+
+ emit_label (diff_label);
+ emit_memcmp_scalar_result_calculation (result, data1, data2);
+ emit_jump_insn (gen_jump (final_label));
+ emit_barrier (); /* No fall-through. */
+
+ emit_label (final_label);
+ return true;
+}
+
+/* Expand memcmp operation.
+
+ RESULT is the register where the return value will be stored.
+ The source pointers are SRC1 and SRC2 (NBYTES bytes to compare). */
+
+bool
+riscv_expand_block_compare (rtx result, rtx src1, rtx src2, rtx nbytes)
+{
+ if (stringop_strategy & STRATEGY_SCALAR)
+ return riscv_expand_block_compare_scalar (result, src1, src2, nbytes);
+
+ return false;
+}
/* Emit straight-line code to move LENGTH bytes from SRC to DEST
with accesses that are ALIGN bytes aligned.
Assume that the areas do not overlap. */
