On Sun, Oct 9, 2016 at 7:53 AM, Samuel Pitoiset
<samuel.pitoi...@gmail.com> wrote:
>
>
> On 10/09/2016 06:12 AM, Ilia Mirkin wrote:
>>
>> A function with multiple returns would have had multiple preret settings
>> at the top of the function. While this is unlikely to have caused issues
>> since we don't use funcitons in earnest, it could have in some cases
>
>
> s/funcitons/functions/ :)
>
> This looks good to me, but fyi this doesn't fix the regressions introduced
> with "nv50/ir: start LocalCSE with getFirst to merge PHI instructions".
> Something else is probably wrong.
I don't think I ever suggested it would. Just something I happened to
notice when looking at the compiled output of a shader. The only case
it could possibly fix is if there were >N preret's, which would
overflow the call stack and probably cause an error.
>
> Reviewed-by: Samuel Pitoiset <samuel.pitoi...@gmail.com>
Thanks!
>
>
>> overflowed the call stack, in case a function had a lot of early
>> returns.
>>
>> Signed-off-by: Ilia Mirkin <imir...@alum.mit.edu>
>> ---
>> src/gallium/drivers/nouveau/codegen/nv50_ir_from_tgsi.cpp | 11
>> +++++++----
>> 1 file changed, 7 insertions(+), 4 deletions(-)
>>
>> 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 5938226..6664366 100644
>> --- a/src/gallium/drivers/nouveau/codegen/nv50_ir_from_tgsi.cpp
>> +++ b/src/gallium/drivers/nouveau/codegen/nv50_ir_from_tgsi.cpp
>> @@ -3475,10 +3475,13 @@ Converter::handleInstruction(const struct
>> tgsi_full_instruction *insn)
>> if (!isEndOfSubroutine(ip + 1)) {
>> // insert a PRERET at the entry if this is an early return
>> // (only needed for sharing code in the epilogue)
>> - BasicBlock *pos = getBB();
>> - setPosition(BasicBlock::get(func->cfg.getRoot()), false);
>> - mkFlow(OP_PRERET, leave, CC_ALWAYS, NULL)->fixed = 1;
>> - setPosition(pos, true);
>> + BasicBlock *root = BasicBlock::get(func->cfg.getRoot());
>> + if (root->getEntry() != NULL && root->getEntry()->op !=
>> OP_PRERET) {
>> + BasicBlock *pos = getBB();
>> + setPosition(root, false);
>> + mkFlow(OP_PRERET, leave, CC_ALWAYS, NULL)->fixed = 1;
>> + setPosition(pos, true);
>> + }
>> }
>> mkFlow(OP_RET, NULL, CC_ALWAYS, NULL)->fixed = 1;
>> bb->cfg.attach(&leave->cfg, Graph::Edge::CROSS);
>>
>
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