From: Christoph Bumiller <e0425955@student.tuwien.ac.at>
Date: Wed, 27 Feb 2013 20:08:57 +0000 (+0100)
Subject: nv50/ir/ra: make sure all used function inputs get assigned a reg
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=e9294e11b452e8ad159496abecf7fd0f406b0fe2;p=mesa.git

nv50/ir/ra: make sure all used function inputs get assigned a reg

A live range [0, 0) counts as empty. For function inputs this can
be a problem, so insert a nop at the beginning to make it [0, 1).
This is a bit of a hack but also the most simple solution.
---

diff --git a/src/gallium/drivers/nv50/codegen/nv50_ir_ra.cpp b/src/gallium/drivers/nv50/codegen/nv50_ir_ra.cpp
index 5e5255fc4f8..e0fea4b9337 100644
--- a/src/gallium/drivers/nv50/codegen/nv50_ir_ra.cpp
+++ b/src/gallium/drivers/nv50/codegen/nv50_ir_ra.cpp
@@ -1586,6 +1586,13 @@ RegAlloc::execFunc()
    unsigned int i, retries;
    bool ret;
 
+   if (!func->ins.empty()) {
+      // Insert a nop at the entry so inputs only used by the first instruction
+      // don't count as having an empty live range.
+      Instruction *nop = new_Instruction(func, OP_NOP, TYPE_NONE);
+      BasicBlock::get(func->cfg.getRoot())->insertHead(nop);
+   }
+
    ret = insertConstr.exec(func);
    if (!ret)
       goto out;