swr/rast: Fix alloca usage in jitter

Fix issue where temporary allocas were getting hoisted to function entry
unnecessarily. We now explicitly mark temporary allocas and skip hoisting
during the hoist pass. Shuold reduce stack usage.

Reviewed-by: Bruce Cherniak <[email protected]>

1 files changed, 17 insertions, 0 deletions

diff --git a/src/gallium/drivers/swr/rasterizer/jitter/builder.cpp b/src/gallium/drivers/swr/rasterizer/jitter/builder.cpp
index 53947c317e2..bd815606fba 100644
--- a/src/gallium/drivers/swr/rasterizer/jitter/builder.cpp
+++ b/src/gallium/drivers/swr/rasterizer/jitter/builder.cpp
@@ -111,4 +111,21 @@ namespace SwrJit
         mSimdVectorIntTy = ArrayType::get(mSimdInt32Ty, 4);
         mSimdVectorTRTy = ArrayType::get(mSimdFP32Ty, 5);
     }
+
+    /// @brief Mark this alloca as temporary to avoid hoisting later on
+    void Builder::SetTempAlloca(Value* inst)
+    {
+        AllocaInst* pAlloca = dyn_cast<AllocaInst>(inst);
+        SWR_ASSERT(pAlloca, "Unexpected non-alloca instruction");
+        MDNode* N = MDNode::get(JM()->mContext, MDString::get(JM()->mContext, "is_temp_alloca"));
+        pAlloca->setMetadata("is_temp_alloca", N);
+    }
+
+    bool Builder::IsTempAlloca(Value* inst)
+    {
+        AllocaInst* pAlloca = dyn_cast<AllocaInst>(inst);
+        SWR_ASSERT(pAlloca, "Unexpected non-alloca instruction");
+
+        return (pAlloca->getMetadata("is_temp_alloca") != nullptr);
+    }
 }