radeonsi: Fix w component of TGSI_SEMANTIC_POSITION fragment shader inputs.
It's the reciprocal of the register value.
Fixes piglit fragcoord_w and glsl-fs-fragcoord-zw-perspective.
NOTE: This is a candidate for the 9.1 branch.
diff --git a/src/gallium/drivers/radeonsi/radeonsi_shader.c b/src/gallium/drivers/radeonsi/radeonsi_shader.c
index 704f859..7922928 100644
--- a/src/gallium/drivers/radeonsi/radeonsi_shader.c
+++ b/src/gallium/drivers/radeonsi/radeonsi_shader.c
@@ -263,6 +263,14 @@
build_intrinsic(base->gallivm->builder,
"llvm.SI.fs.read.pos", input_type,
args, 1, LLVMReadNoneAttribute);
+
+ if (chan == 3)
+ /* RCP for fragcoord.w */
+ si_shader_ctx->radeon_bld.inputs[soa_index] =
+ LLVMBuildFDiv(gallivm->builder,
+ lp_build_const_float(gallivm, 1.0f),
+ si_shader_ctx->radeon_bld.inputs[soa_index],
+ "");
}
return;
}