From a1754424b6597219f436091dec1de4713719c4b8 Mon Sep 17 00:00:00 2001 From: Brian Paul Date: Mon, 27 Oct 2008 15:58:00 -0600 Subject: [PATCH] gallium: ppc: emit fewer 'li' instructions prior to vector loads/stores --- src/gallium/auxiliary/tgsi/tgsi_ppc.c | 106 ++++++++++++++++++++++++---------- 1 file changed, 75 insertions(+), 31 deletions(-) diff --git a/src/gallium/auxiliary/tgsi/tgsi_ppc.c b/src/gallium/auxiliary/tgsi/tgsi_ppc.c index 000ddba9359..06b7a41b1b9 100644 --- a/src/gallium/auxiliary/tgsi/tgsi_ppc.c +++ b/src/gallium/auxiliary/tgsi/tgsi_ppc.c @@ -95,6 +95,9 @@ struct gen_context int const_reg; /**< GP register pointing to constants buffer */ int builtins_reg; /**< GP register pointint to built-in constants */ + int offset_reg; /**< used to reduce redundant li instructions */ + int offset_value; + int one_vec; /**< vector register with {1.0, 1.0, 1.0, 1.0} */ int bit31_vec; /**< vector register with {1<<31, 1<<31, 1<<31, 1<<31} */ @@ -113,6 +116,70 @@ struct gen_context /** + * Initialize code generation context. + */ +static void +init_gen_context(struct gen_context *gen, struct ppc_function *func) +{ + memset(gen, 0, sizeof(*gen)); + gen->f = func; + gen->inputs_reg = ppc_reserve_register(func, 3); /* first function param */ + gen->outputs_reg = ppc_reserve_register(func, 4); /* second function param */ + gen->temps_reg = ppc_reserve_register(func, 5); /* ... */ + gen->immed_reg = ppc_reserve_register(func, 6); + gen->const_reg = ppc_reserve_register(func, 7); + gen->builtins_reg = ppc_reserve_register(func, 8); + gen->one_vec = -1; + gen->bit31_vec = -1; + gen->offset_reg = -1; + gen->offset_value = -9999999; +} + + +/** + * All PPC vector load/store instructions form an effective address + * by adding the contents of two registers. For example: + * lvx v2,r8,r9 # v2 = memory[r8 + r9] + * stvx v2,r8,r9 # memory[r8 + r9] = v2; + * So our lvx/stvx instructions are typically preceded by an 'li' instruction + * to load r9 (above) with an immediate (an offset). + * This code emits that 'li' instruction, but only if the offset value is + * different than the previous 'li'. + * This optimization seems to save about 10% in the instruction count. + * Note that we need to unconditionally emit an 'li' inside basic blocks + * (such as inside loops). + */ +static int +emit_li_offset(struct gen_context *gen, int offset) +{ + if (gen->offset_reg <= 0) { + /* allocate a GP register for storing load/store offset */ + gen->offset_reg = ppc_allocate_register(gen->f); + } + + /* emit new 'li' if offset is changing */ + if (gen->offset_value < 0 || gen->offset_value != offset) { + gen->offset_value = offset; + ppc_li(gen->f, gen->offset_reg, offset); + } + + return gen->offset_reg; +} + + +/** + * Forces subsequent emit_li_offset() calls to emit an 'li'. + * To be called at the top of basic blocks. + */ +static int +reset_li_offset(struct gen_context *gen) +{ + gen->offset_value = -9999999; +} + + + +/** * Load the given vector register with {value, value, value, value}. * The value must be in the ppu_builtin_constants[] array. * We wouldn't need this if there was a simple way to load PPC vector @@ -124,10 +191,9 @@ load_constant_vec(struct gen_context *gen, int dst_vec, float value) uint pos; for (pos = 0; pos < Elements(ppc_builtin_constants); pos++) { if (ppc_builtin_constants[pos] == value) { - int offset_reg = ppc_allocate_register(gen->f); int offset = pos * 4; + int offset_reg = emit_li_offset(gen, offset); - ppc_li(gen->f, offset_reg, offset); /* Load 4-byte word into vector register. * The vector slot depends on the effective address we load from. * We know that our builtins start at a 16-byte boundary so we @@ -137,7 +203,6 @@ load_constant_vec(struct gen_context *gen, int dst_vec, float value) ppc_lvewx(gen->f, dst_vec, gen->builtins_reg, offset_reg); /* splat word[pos % 4] across the vector reg */ ppc_vspltw(gen->f, dst_vec, dst_vec, pos % 4); - ppc_release_register(gen->f, offset_reg); return; } } @@ -192,36 +257,29 @@ emit_fetch(struct gen_context *gen, switch (reg->SrcRegister.File) { case TGSI_FILE_INPUT: { - int offset_reg = ppc_allocate_register(gen->f); int offset = (reg->SrcRegister.Index * 4 + swizzle) * 16; - ppc_li(gen->f, offset_reg, offset); + int offset_reg = emit_li_offset(gen, offset); ppc_lvx(gen->f, dst_vec, gen->inputs_reg, offset_reg); - ppc_release_register(gen->f, offset_reg); } break; case TGSI_FILE_TEMPORARY: { - int offset_reg = ppc_allocate_register(gen->f); int offset = (reg->SrcRegister.Index * 4 + swizzle) * 16; - ppc_li(gen->f, offset_reg, offset); + int offset_reg = emit_li_offset(gen, offset); ppc_lvx(gen->f, dst_vec, gen->temps_reg, offset_reg); - ppc_release_register(gen->f, offset_reg); } break; case TGSI_FILE_IMMEDIATE: { - int offset_reg = ppc_allocate_register(gen->f); int offset = (reg->SrcRegister.Index * 4 + swizzle) * 16; - ppc_li(gen->f, offset_reg, offset); + int offset_reg = emit_li_offset(gen, offset); ppc_lvx(gen->f, dst_vec, gen->immed_reg, offset_reg); - ppc_release_register(gen->f, offset_reg); } break; case TGSI_FILE_CONSTANT: { - int offset_reg = ppc_allocate_register(gen->f); int offset = (reg->SrcRegister.Index * 4 + swizzle) * 4; - ppc_li(gen->f, offset_reg, offset); + int offset_reg = emit_li_offset(gen, offset); /* Load 4-byte word into vector register. * The vector slot depends on the effective address we load from. * We know that our constants start at a 16-byte boundary so we @@ -231,7 +289,6 @@ emit_fetch(struct gen_context *gen, ppc_lvewx(gen->f, dst_vec, gen->const_reg, offset_reg); /* splat word[swizzle] across the vector reg */ ppc_vspltw(gen->f, dst_vec, dst_vec, swizzle); - ppc_release_register(gen->f, offset_reg); } break; default: @@ -369,20 +426,16 @@ emit_store(struct gen_context *gen, switch (reg->DstRegister.File) { case TGSI_FILE_OUTPUT: { - int offset_reg = ppc_allocate_register(gen->f); int offset = (reg->DstRegister.Index * 4 + chan_index) * 16; - ppc_li(gen->f, offset_reg, offset); + int offset_reg = emit_li_offset(gen, offset); ppc_stvx(gen->f, src_vec, gen->outputs_reg, offset_reg); - ppc_release_register(gen->f, offset_reg); } break; case TGSI_FILE_TEMPORARY: { - int offset_reg = ppc_allocate_register(gen->f); int offset = (reg->DstRegister.Index * 4 + chan_index) * 16; - ppc_li(gen->f, offset_reg, offset); + int offset_reg = emit_li_offset(gen, offset); ppc_stvx(gen->f, src_vec, gen->temps_reg, offset_reg); - ppc_release_register(gen->f, offset_reg); } break; #if 0 @@ -946,16 +999,7 @@ tgsi_emit_ppc(const struct tgsi_token *tokens, util_init_math(); - memset(&gen, 0, sizeof(gen)); - gen.f = func; - gen.inputs_reg = ppc_reserve_register(func, 3); /* first function param */ - gen.outputs_reg = ppc_reserve_register(func, 4); /* second function param */ - gen.temps_reg = ppc_reserve_register(func, 5); /* ... */ - gen.immed_reg = ppc_reserve_register(func, 6); - gen.const_reg = ppc_reserve_register(func, 7); - gen.builtins_reg = ppc_reserve_register(func, 8); - gen.one_vec = -1; - gen.bit31_vec = -1; + init_gen_context(&gen, func); emit_prologue(func); -- 2.11.0