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| author | Roger Sayle <roger@nextmovesoftware.com> | 2024-08-28 21:19:28 -0600 |
|---|---|---|
| committer | Roger Sayle <roger@nextmovesoftware.com> | 2024-08-28 21:19:28 -0600 |
| commit | 3cb92be94e6581697369eeafdb67057c8cfba73f (patch) | |
| tree | acb838815e6ecbc2aaed7ffa35bfb51514843988 /gcc | |
| parent | 155da081706e0e0527f01ad565b1cd6c217f5880 (diff) | |
| download | gcc-3cb92be94e6581697369eeafdb67057c8cfba73f.zip gcc-3cb92be94e6581697369eeafdb67057c8cfba73f.tar.gz gcc-3cb92be94e6581697369eeafdb67057c8cfba73f.tar.bz2 | |
i386: Support wide immediate constants in STV.
This patch provides more accurate costs/gains for (wide) immediate
constants in STV, suitably adjusting the costs/gains when the highpart
and lowpart words are the same.
2024-08-28 Roger Sayle <roger@nextmovesoftware.com>
gcc/ChangeLog
* config/i386/i386-features.cc (timode_immed_const_gain): New
function to determine the gain/cost on a CONST_WIDE_INT.
(timode_scalar_chain::compute_convert_gain): Fix whitespace.
<case CONST_WIDE_INT>: Provide more accurate estimates using
timode_immed_const_gain.
<case AND>: Handle CONSTANT_SCALAR_INT_P (src).
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/config/i386/i386-features.cc | 28 |
1 files changed, 27 insertions, 1 deletions
diff --git a/gcc/config/i386/i386-features.cc b/gcc/config/i386/i386-features.cc index ca902ec..c09a5c7 100644 --- a/gcc/config/i386/i386-features.cc +++ b/gcc/config/i386/i386-features.cc @@ -1503,6 +1503,23 @@ general_scalar_chain::convert_insn (rtx_insn *insn) df_insn_rescan (insn); } +/* Helper function to compute gain for loading an immediate constant. + Typically, two movabsq for TImode vs. vmovdqa for V1TImode, but + with numerous special cases. */ + +static int +timode_immed_const_gain (rtx cst) +{ + /* movabsq vs. movabsq+vmovq+vunpacklqdq. */ + if (CONST_WIDE_INT_P (cst) + && CONST_WIDE_INT_NUNITS (cst) == 2 + && CONST_WIDE_INT_ELT (cst, 0) == CONST_WIDE_INT_ELT (cst, 1)) + return optimize_insn_for_size_p () ? -COSTS_N_BYTES (9) + : -COSTS_N_INSNS (2); + /* 2x movabsq ~ vmovdqa. */ + return 0; +} + /* Compute a gain for chain conversion. */ int @@ -1549,7 +1566,14 @@ timode_scalar_chain::compute_convert_gain () case CONST_INT: if (MEM_P (dst) && standard_sse_constant_p (src, V1TImode)) - igain = optimize_insn_for_size_p() ? COSTS_N_BYTES (11) : 1; + igain = optimize_insn_for_size_p () ? COSTS_N_BYTES (11) : 1; + break; + + case CONST_WIDE_INT: + /* 2 x mov vs. vmovdqa. */ + if (MEM_P (dst)) + igain = optimize_insn_for_size_p () ? COSTS_N_BYTES (3) + : COSTS_N_INSNS (1); break; case NOT: @@ -1562,6 +1586,8 @@ timode_scalar_chain::compute_convert_gain () case IOR: if (!MEM_P (dst)) igain = COSTS_N_INSNS (1); + if (CONST_SCALAR_INT_P (XEXP (src, 1))) + igain += timode_immed_const_gain (XEXP (src, 1)); break; case ASHIFT: |