From 553700cf55712ae7269ec4225310a2bf0539f64e Mon Sep 17 00:00:00 2001 From: Iago Toral Quiroga Date: Wed, 24 Aug 2016 11:21:57 +0200 Subject: [PATCH] i965/vec4: Fix DCE for VEC4_OPCODE_SET_{LOW,HIGH}_32BIT These align1 opcodes do partial writes of 64-bit data. The problem is that we want to use them to write on the same register to implement packDouble2x32 and from the point of view of DCE, since both opcodes write to the same register, only the last one stands and decides to eliminate the first, which is not correct, so prevent this from happening. v2: Make a helper in vec4_instruction to know if the instruction is an align1 partial write. This will come in handy when we implement a simd splitting pass in a later patch. Reviewed-by: Ian Romanick Reviewed-by: Matt Turner --- src/mesa/drivers/dri/i965/brw_ir_vec4.h | 6 ++++++ src/mesa/drivers/dri/i965/brw_vec4_dead_code_eliminate.cpp | 3 ++- 2 files changed, 8 insertions(+), 1 deletion(-) diff --git a/src/mesa/drivers/dri/i965/brw_ir_vec4.h b/src/mesa/drivers/dri/i965/brw_ir_vec4.h index 5dfdfce..766cec7 100644 --- a/src/mesa/drivers/dri/i965/brw_ir_vec4.h +++ b/src/mesa/drivers/dri/i965/brw_ir_vec4.h @@ -280,6 +280,12 @@ public: bool can_change_types() const; bool has_source_and_destination_hazard() const; + bool is_align1_partial_write() + { + return opcode == VEC4_OPCODE_SET_LOW_32BIT || + opcode == VEC4_OPCODE_SET_HIGH_32BIT; + } + bool reads_flag() { return predicate || opcode == VS_OPCODE_UNPACK_FLAGS_SIMD4X2; diff --git a/src/mesa/drivers/dri/i965/brw_vec4_dead_code_eliminate.cpp b/src/mesa/drivers/dri/i965/brw_vec4_dead_code_eliminate.cpp index 65f9f38..9185d52 100644 --- a/src/mesa/drivers/dri/i965/brw_vec4_dead_code_eliminate.cpp +++ b/src/mesa/drivers/dri/i965/brw_vec4_dead_code_eliminate.cpp @@ -110,7 +110,8 @@ vec4_visitor::dead_code_eliminate() } } - if (inst->dst.file == VGRF && !inst->predicate) { + if (inst->dst.file == VGRF && !inst->predicate && + !inst->is_align1_partial_write()) { for (unsigned i = 0; i < regs_written(inst); i++) { for (int c = 0; c < 4; c++) { if (inst->dst.writemask & (1 << c)) { -- 2.7.4