Discussion:
[PATCH v2] nv50/ir: clean up saturated values immediately
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Ilia Mirkin
2017-08-12 17:55:16 UTC
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Raw Message
Since we don't iterate to a fixed point, we can end up in situations
where we have a SAT instruction + a long immediate. This is not legal.
However since it's immediately computable, just run unary straight away
to handle the situation.

Fixes: 24a799ad35a82 ("nv50/ir: fix ConstantFolding with saturation")
Reported-by: Tobias Klausmann <***@mni.thm.de>
Signed-off-by: Ilia Mirkin <***@alum.mit.edu>
---

v1 -> v2:
use the more complete getImmediate() when we don't know for sure that
the argument is an actual ImmediateValue, to pick up potential additional
cases.

src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp b/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
index cfc0dfc53cf..7e4e193e3d2 100644
--- a/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
+++ b/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
@@ -727,7 +727,9 @@ ConstantFolding::expr(Instruction *i,
// Leave PFETCH alone... we just folded its 2 args into 1.
break;
default:
- i->op = i->saturate ? OP_SAT : OP_MOV; /* SAT handled by unary() */
+ i->op = i->saturate ? OP_SAT : OP_MOV;
+ if (i->saturate)
+ unary(i, *i->getSrc(0)->asImm());
break;
}
i->subOp = 0;
@@ -1513,8 +1515,11 @@ ConstantFolding::opnd(Instruction *i, ImmediateValue &imm0, int s)
// This can get left behind some of the optimizations which simplify
// saturatable values.
if (newi->op == OP_MOV && newi->saturate) {
+ ImmediateValue tmp;
newi->saturate = 0;
newi->op = OP_SAT;
+ if (newi->src(0).getImmediate(tmp))
+ unary(newi, tmp);
}

if (newi->op != op)
--
2.13.0
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