Module: Mesa Branch: master Commit: fa84296a5a7c707e87299c921acde3bd1533833f URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=fa84296a5a7c707e87299c921acde3bd1533833f
Author: Nicolai Hähnle <[email protected]> Date: Mon Aug 8 22:15:04 2016 +0200 gallium/radeon: clarify the comment on the array alloca heuristic Reviewed-by: Marek Olšák <[email protected]> --- .../drivers/radeon/radeon_setup_tgsi_llvm.c | 29 ++++++++++++++-------- 1 file changed, 19 insertions(+), 10 deletions(-) diff --git a/src/gallium/drivers/radeon/radeon_setup_tgsi_llvm.c b/src/gallium/drivers/radeon/radeon_setup_tgsi_llvm.c index 22ff18e..e4bfa74 100644 --- a/src/gallium/drivers/radeon/radeon_setup_tgsi_llvm.c +++ b/src/gallium/drivers/radeon/radeon_setup_tgsi_llvm.c @@ -444,19 +444,28 @@ static void emit_declaration(struct lp_build_tgsi_context *bld_base, ctx->arrays[id].range = decl->Range; - /* If the array is more than 16 elements (each element - * is 32-bits), then store it in a vector. Storing the - * array in a vector will causes the compiler to store - * the array in registers and access it using indirect - * addressing. 16 is number of vector elements that - * LLVM will store in a register. - * FIXME: We shouldn't need to do this. LLVM should be - * smart enough to promote allocas int registers when - * profitable. + /* If the array has more than 16 elements, store it + * in memory using an alloca that spans the entire + * array. + * + * Otherwise, store each array element individually. + * We will then generate vectors (per-channel, up to + * <4 x float>) for indirect addressing. + * + * Note that 16 is the number of vector elements that + * LLVM will store in a register, so theoretically an + * array with up to 4 * 16 = 64 elements could be + * handled this way, but whether that's a good idea + * depends on VGPR register pressure elsewhere. + * + * FIXME: We shouldn't need to have the non-alloca + * code path for arrays. LLVM should be smart enough to + * promote allocas into registers when profitable. */ if (decl_size > 16) { array_alloca = LLVMBuildAlloca(builder, - LLVMArrayType(bld_base->base.vec_type, decl_size),"array"); + LLVMArrayType(bld_base->base.vec_type, + decl_size), "array"); ctx->arrays[id].alloca = array_alloca; } } _______________________________________________ mesa-commit mailing list [email protected] https://lists.freedesktop.org/mailman/listinfo/mesa-commit
