From 4d456e4d34b1e4fb3725051d1b8a0c376b704692 Mon Sep 17 00:00:00 2001
From: Tom Smeding <tom@tomsmeding.com>
Date: Thu, 30 Oct 2025 15:56:35 +0100
Subject: Implement reshape

---
 src/Compile.hs | 24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

(limited to 'src/Compile.hs')

diff --git a/src/Compile.hs b/src/Compile.hs
index 0ab7ea4..4e81c6a 100644
--- a/src/Compile.hs
+++ b/src/Compile.hs
@@ -920,6 +920,25 @@ compile' env = \case
 
   EMinimum1Inner _ e -> compileExtremum "min" "minimum1i" "<" env e
 
+  EReshape _ dim esh earg -> do
+    let STArr origDim eltty = typeOf earg
+    strname <- emitStruct (STArr dim eltty)
+
+    shname <- compileAssign "reshsh" env esh
+    arrname <- compileAssign "resharg" env earg
+
+    when emitChecks $ do
+      emit $ SIf (CEBinop (compileArrShapeSize origDim arrname) "!=" (CECast "size_t" (prodExpr (indexTupleComponents dim shname))))
+                 (pure $ SVerbatim $
+                    "fprintf(stderr, PRTAG \"CHECK: reshape on unequal sizes (%zu <- %zu)\\n\", " ++
+                      printCExpr 0 (prodExpr (indexTupleComponents dim shname)) ", " ++
+                      printCExpr 0 (compileArrShapeSize origDim arrname) "); return false;")
+                 mempty
+
+    return (CEStruct strname
+              [("buf", CEProj (CELit arrname) "buf")
+              ,("sh", CELit ("{" ++ intercalate ", " [printCExpr 0 e "" | e <- indexTupleComponents dim shname] ++ "}"))])
+
   EConst _ t x -> return $ CELit $ compileScal True t x
 
   EIdx0 _ e -> do
@@ -1323,7 +1342,7 @@ compileShapeQuery (SS n) var =
 
 -- | Takes a variable name for the array, not the buffer.
 compileArrShapeSize :: SNat n -> String -> CExpr
-compileArrShapeSize n var = foldl0' (\a b -> CEBinop a "*" b) (CELit "1") (compileArrShapeComponents n var)
+compileArrShapeSize n var = prodExpr (compileArrShapeComponents n var)
 
 -- | Takes a variable name for the array, not the buffer.
 compileArrShapeComponents :: SNat n -> String -> [CExpr]
@@ -1347,6 +1366,9 @@ shapeTupFromLitVars = \n -> go n . reverse
     go (SS n) (var : vars) = CEStruct (repSTy (tTup (sreplicate (SS n) tIx))) [("a", go n vars), ("b", CELit var)]
     go _ _ = error "shapeTupFromLitVars: SNat and list do not correspond"
 
+prodExpr :: [CExpr] -> CExpr
+prodExpr = foldl0' (\a b -> CEBinop a "*" b) (CELit "1")
+
 compileOpGeneral :: SOp a b -> CExpr -> CompM CExpr
 compileOpGeneral op e1 = do
   let unary cop = return @CompM $ CECall cop [e1]
-- 
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