[Mesa-dev] [PATCH mesa v2] nouveau: codegen: combineLd/St do not combine indirect loads

[Hans de Goede]

combineLd/St would combine, i.e. :

st  u32 # g[$r2+0x0] $r2
st  u32 # g[$r2+0x4] $r3

into:

st  u64 # g[$r2+0x0] $r2d

But this is only valid if r2 contains an 8 byte aligned address,
which is not guaranteed for compute shaders

This commit checks for src0 dim 0 not being indirect when combining
loads / stores as combining indirect loads / stores may break alignment
rules.

Signed-off-by: Hans de Goede <hdegoede at redhat.com>
---
Changes in v2:
-Only check for indirect loads/stores in the compute case
---
 src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp b/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
index 6ec5fa5..9ce062e 100644
--- a/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
+++ b/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
@@ -2216,6 +2216,9 @@ MemoryOpt::combineLd(Record *rec, Instruction *ld)
    if (((size == 0x8) && (MIN2(offLd, offRc) & 0x7)) ||
        ((size == 0xc) && (MIN2(offLd, offRc) & 0xf)))
       return false;
+   // for compute indirect loads are not guaranteed to be aligned
+   if (prog->getType() == Program::TYPE_COMPUTE && rec->rel[0])
+      return false;
 
    assert(sizeRc + sizeLd <= 16 && offRc != offLd);
 
@@ -2268,8 +2271,12 @@ MemoryOpt::combineSt(Record *rec, Instruction *st)
    if (!prog->getTarget()->
        isAccessSupported(st->getSrc(0)->reg.file, typeOfSize(size)))
       return false;
+   // no unaligned stores
    if (size == 8 && MIN2(offRc, offSt) & 0x7)
       return false;
+   // for compute indirect stores are not guaranteed to be aligned
+   if (prog->getType() == Program::TYPE_COMPUTE && rec->rel[0])
+      return false;
 
    st->takeExtraSources(0, extra); // save predicate and indirect address
 
-- 
2.7.3