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67 lines
2.3 KiB
67 lines
2.3 KiB
From 508280f7ac31c7d0ab2eaed33b26e6df59bb4dd9 Mon Sep 17 00:00:00 2001
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From: "L. E. Segovia" <amy@centricular.com>
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Date: Fri, 19 Jul 2024 22:25:20 -0300
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Subject: [PATCH 1/2] powerpc: fix div255w which still used the inexact
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substitution
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The code for this architecture used the substitution suggested in the
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original bug report. That one had subtle failures on armv7a and aarch64,
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but I was not able to verify if they affected PowerPC too.
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This commit fixes it by reusing the mulhuw instruction implementation --
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sse2 can be ported directly that way.
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Fixes #71
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Part-of: <https://gitlab.freedesktop.org/gstreamer/orc/-/merge_requests/195>
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---
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orc/orcrules-altivec.c | 31 +++++++++++++++----------------
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1 file changed, 15 insertions(+), 16 deletions(-)
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diff --git a/orc/orcrules-altivec.c b/orc/orcrules-altivec.c
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index 23409a8..a13fb5b 100644
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--- a/orc/orcrules-altivec.c
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+++ b/orc/orcrules-altivec.c
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@@ -1513,23 +1513,22 @@ powerpc_rule_convlf (OrcCompiler *p, void *user, OrcInstruction *insn)
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static void
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powerpc_rule_div255w (OrcCompiler *p, void *user, OrcInstruction *insn)
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{
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- int src1 = ORC_SRC_ARG (p, insn, 0);
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- int dest = ORC_DEST_ARG (p, insn, 0);
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- int tmp = orc_compiler_get_temp_reg (p);
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- int tmp2 = orc_compiler_get_temp_reg (p);
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- int tmpc;
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-
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- tmpc = powerpc_get_constant (p, ORC_CONST_SPLAT_W, 0x0001);
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-
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- ORC_ASM_CODE(p," vspltish %s, 8\n", powerpc_get_regname(tmp2));
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- powerpc_emit_VX(p, 0x1000034c, powerpc_regnum(tmp2), 8, 0);
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-
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- powerpc_emit_VX_2 (p, "vadduhm", 0x10000040, dest, src1, tmpc);
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-
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- powerpc_emit_VX_2 (p, "vsrh", 0x10000244, tmp, src1, tmp2);
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- powerpc_emit_VX_2 (p, "vadduhm", 0x10000040, dest, dest, tmp);
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+ const int src1 = ORC_SRC_ARG (p, insn, 0);
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+ const int dest = ORC_DEST_ARG(p, insn, 0);
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+ const int tmp = powerpc_get_constant (p, ORC_CONST_SPLAT_W, 7);
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+ const int tmpc = powerpc_get_constant (p, ORC_CONST_SPLAT_W, 0x8081);
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+
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+ {
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+ // mulhuw
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+ const int perm = powerpc_get_constant_full(p, 0x10110001, 0x14150405,
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+ 0x18190809, 0x1c1d0c0d);
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+
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+ powerpc_emit_vmuleuh (p, p->tmpreg, src1, tmpc);
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+ powerpc_emit_vmulouh (p, dest, src1, tmpc);
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+ powerpc_emit_vperm (p, dest, dest, p->tmpreg, perm);
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+ }
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- powerpc_emit_VX_2 (p, "vsrh", 0x10000244, dest, dest, tmp2);
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+ powerpc_emit_VX_2 (p, "vsrh", 0x10000244, dest, dest, tmp);
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}
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static void
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--
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2.45.2
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