From c0dfb247b68c2f1485583d6768562711badbc11b Mon Sep 17 00:00:00 2001
From: Dzmitry Malyshau <kvarkus@gmail.com>
Date: Fri, 18 Dec 2020 01:11:47 -0500
Subject: [PATCH] Sizing processor

---
 src/proc/mod.rs      |  2 ++
 src/proc/sizer.rs    | 65 ++++++++++++++++++++++++++++++++++++++++++++
 src/proc/typifier.rs |  1 +
 3 files changed, 68 insertions(+)
 create mode 100644 src/proc/sizer.rs

diff --git a/src/proc/mod.rs b/src/proc/mod.rs
index 74f814a077..ee0baeadaf 100644
--- a/src/proc/mod.rs
+++ b/src/proc/mod.rs
@@ -4,6 +4,7 @@
 mod call_graph;
 mod interface;
 mod namer;
+mod sizer;
 mod terminator;
 mod typifier;
 mod validator;
@@ -12,6 +13,7 @@ mod validator;
 pub use call_graph::{CallGraph, CallGraphBuilder};
 pub use interface::{Interface, Visitor};
 pub use namer::{EntryPointIndex, NameKey, Namer};
+pub use sizer::Sizer;
 pub use terminator::ensure_block_returns;
 pub use typifier::{check_constant_type, ResolveContext, ResolveError, Typifier};
 pub use validator::{ValidationError, Validator};
diff --git a/src/proc/sizer.rs b/src/proc/sizer.rs
new file mode 100644
index 0000000000..a9c58f0912
--- /dev/null
+++ b/src/proc/sizer.rs
@@ -0,0 +1,65 @@
+use crate::arena::Arena;
+
+/// Helper processor that derives the sizes of all types.
+#[derive(Debug)]
+pub struct Sizer {
+    sizes: Vec<u32>,
+}
+
+impl Sizer {
+    pub fn new(types: &Arena<crate::Type>, constants: &Arena<crate::Constant>) -> Self {
+        use crate::TypeInner as Ti;
+
+        let mut sizes = Vec::with_capacity(types.len());
+        for (_, ty) in types.iter() {
+            sizes.push(match ty.inner {
+                Ti::Scalar { kind: _, width } => width as u32,
+                Ti::Vector {
+                    size,
+                    kind: _,
+                    width,
+                } => (size as u8 * width) as u32,
+                Ti::Matrix {
+                    columns,
+                    rows,
+                    width,
+                } => (columns as u8 * rows as u8 * width) as u32,
+                Ti::Pointer { .. } => 0,
+                Ti::Array { base, size, stride } => {
+                    let count = match size {
+                        crate::ArraySize::Constant(handle) => match constants[handle].inner {
+                            crate::ConstantInner::Uint(value) => value as u32,
+                            ref other => unreachable!("Unexpected array size {:?}", other),
+                        },
+                        crate::ArraySize::Dynamic => 1,
+                    };
+                    let stride = match stride {
+                        Some(value) => value.get(),
+                        None => sizes[base.index()],
+                    };
+                    count * stride
+                }
+                Ti::Struct {
+                    block: _,
+                    ref members,
+                } => {
+                    let mut total = 0;
+                    for member in members {
+                        total += match member.span {
+                            Some(span) => span.get(),
+                            None => sizes[member.ty.index()],
+                        };
+                    }
+                    total
+                }
+                Ti::Image { .. } | Ti::Sampler { .. } => 0,
+            });
+        }
+
+        Sizer { sizes }
+    }
+
+    pub fn resolve(&self, handle: crate::Handle<crate::Type>) -> u32 {
+        self.sizes[handle.index()]
+    }
+}
diff --git a/src/proc/typifier.rs b/src/proc/typifier.rs
index c8ee18b1da..6862773c55 100644
--- a/src/proc/typifier.rs
+++ b/src/proc/typifier.rs
@@ -36,6 +36,7 @@ impl Clone for Resolution {
     }
 }
 
+/// Helper processor that derives the types of all expressions.
 #[derive(Debug)]
 pub struct Typifier {
     resolutions: Vec<Resolution>,