[Mesa-dev] [PATCH mesa v2 3/3] nouveau: codegen: LOAD: Take src swizzle into account

[Hans de Goede]

The llvm TGSI backend uses pointers in registers and does things
like:

LOAD TEMP[0].y, MEMORY[0], TEMP[0]

Expecting the data at address TEMP[0].x to get loaded to
TEMP[0].y. But this will cause the data at TEMP[0].x + 4 to be
loaded instead.

This commit adds support for a swizzle suffix for the 1st source
operand, which allows using:

LOAD TEMP[0].y, MEMORY[0].xxxx, TEMP[0]

And actually getting the desired behavior

Signed-off-by: Hans de Goede <hdegoede at redhat.com>
---
Changes in v2:
-Tweaked commit msg a bit
-Add documentation for this to src/gallium/docs/source/tgsi.rst
---
 src/gallium/docs/source/tgsi.rst                          | 3 +++
 src/gallium/drivers/nouveau/codegen/nv50_ir_from_tgsi.cpp | 8 ++++++--
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/src/gallium/docs/source/tgsi.rst b/src/gallium/docs/source/tgsi.rst
index 85c302f..4315707 100644
--- a/src/gallium/docs/source/tgsi.rst
+++ b/src/gallium/docs/source/tgsi.rst
@@ -2288,6 +2288,9 @@ Resource Access Opcodes
                texture arrays and 2D textures.  address.w is always
                ignored.
 
+               A swizzle suffix may be added to the resource argument
+               this will cause the resource data to be swizzled accordingly.
+
 .. opcode:: STORE - Write data to a shader resource
 
                Syntax: ``STORE resource, address, src``
diff --git a/src/gallium/drivers/nouveau/codegen/nv50_ir_from_tgsi.cpp b/src/gallium/drivers/nouveau/codegen/nv50_ir_from_tgsi.cpp
index e2db731..01df4f3 100644
--- a/src/gallium/drivers/nouveau/codegen/nv50_ir_from_tgsi.cpp
+++ b/src/gallium/drivers/nouveau/codegen/nv50_ir_from_tgsi.cpp
@@ -2279,13 +2279,17 @@ Converter::handleLOAD(Value *dst0[4])
 
          Value *off;
          Symbol *sym;
+         uint32_t src0_component_offset = tgsi.getSrc(0).getSwizzle(c) * 4;
+
          if (tgsi.getSrc(1).getFile() == TGSI_FILE_IMMEDIATE) {
             off = NULL;
             sym = makeSym(tgsi.getSrc(0).getFile(), r, -1, c,
-                          tgsi.getSrc(1).getValueU32(0, info) + 4 * c);
+                          tgsi.getSrc(1).getValueU32(0, info) +
+                          src0_component_offset);
          } else {
             off = fetchSrc(1, 0);
-            sym = makeSym(tgsi.getSrc(0).getFile(), r, -1, c, 4 * c);
+            sym = makeSym(tgsi.getSrc(0).getFile(), r, -1, c,
+                          src0_component_offset);
          }
 
          Instruction *ld = mkLoad(TYPE_U32, dst0[c], sym, off);
-- 
2.7.3