[Mesa-dev] [PATCH 1/8] swr/rast: Allow gather of floats from fetch shader with 2-4GB offsets

[Tim Rowley]

---
 src/gallium/drivers/swr/rasterizer/codegen/gen_llvm_ir_macros.py | 1 +
 src/gallium/drivers/swr/rasterizer/jitter/fetch_jit.cpp          | 7 ++++++-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/gallium/drivers/swr/rasterizer/codegen/gen_llvm_ir_macros.py b/src/gallium/drivers/swr/rasterizer/codegen/gen_llvm_ir_macros.py
index 2ed2b2f..025d38a 100644
--- a/src/gallium/drivers/swr/rasterizer/codegen/gen_llvm_ir_macros.py
+++ b/src/gallium/drivers/swr/rasterizer/codegen/gen_llvm_ir_macros.py
@@ -45,6 +45,7 @@ intrinsics = [
         ['VGATHERPD', 'x86_avx2_gather_d_pd_256', ['src', 'pBase', 'indices', 'mask', 'scale']],
         ['VGATHERPS', 'x86_avx2_gather_d_ps_256', ['src', 'pBase', 'indices', 'mask', 'scale']],
         ['VGATHERDD', 'x86_avx2_gather_d_d_256', ['src', 'pBase', 'indices', 'mask', 'scale']],
+        ['VPSRLI', 'x86_avx2_psrli_d', ['src', 'imm']],
         ['VSQRTPS', 'x86_avx_sqrt_ps_256', ['a']],
         ['VRSQRTPS', 'x86_avx_rsqrt_ps_256', ['a']],
         ['VRCPPS', 'x86_avx_rcp_ps_256', ['a']],
diff --git a/src/gallium/drivers/swr/rasterizer/jitter/fetch_jit.cpp b/src/gallium/drivers/swr/rasterizer/jitter/fetch_jit.cpp
index dcfe897..761c58c 100644
--- a/src/gallium/drivers/swr/rasterizer/jitter/fetch_jit.cpp
+++ b/src/gallium/drivers/swr/rasterizer/jitter/fetch_jit.cpp
@@ -1005,7 +1005,12 @@ void FetchJit::JitGatherVertices(const FETCH_COMPILE_STATE &fetchState,
                                 Value *vMask = vGatherMask;
 
                                 // Gather a SIMD of vertices
-                                vVertexElements[currentVertexElement++] = GATHERPS(gatherSrc, pStreamBase, vOffsets, vMask, C((char)1));
+                                // APIs allow a 4GB range for offsets
+                                // However, GATHERPS uses signed 32-bit offsets, so only a 2GB range :(
+                                // But, we know that elements must be aligned for FETCH. :)
+                                // Right shift the offset by a bit and then scale by 2 to remove the sign extension.
+                                Value* vShiftedOffsets = VPSRLI(vOffsets, C(1));
+                                vVertexElements[currentVertexElement++] = GATHERPS(gatherSrc, pStreamBase, vShiftedOffsets, vMask, C((char)2));
                             }
                             else
                             {
-- 
2.7.4