From 82a3d6068bce5ad794b9f2a2a5405f470860568c Mon Sep 17 00:00:00 2001
From: Gleb Koval <gleb@koval.net>
Date: Thu, 27 Feb 2025 15:46:01 +0000
Subject: [PATCH] fix: zero-out sub-32 bit expressions

---
 src/main/wacc/backend/asmGenerator.scala | 9 ++++++---
 src/test/wacc/examples.scala             | 5 ++---
 2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/src/main/wacc/backend/asmGenerator.scala b/src/main/wacc/backend/asmGenerator.scala
index cd53b30..8dc67f6 100644
--- a/src/main/wacc/backend/asmGenerator.scala
+++ b/src/main/wacc/backend/asmGenerator.scala
@@ -41,8 +41,6 @@ object asmGenerator {
   private val RCX = Register(Q64, CX)
   private val argRegs = List(DI, SI, DX, CX, R8, R9)
 
-  private val _8_BIT_MASK = 0xff
-
   extension [T](chain: Chain[T])
     def +(item: T): Chain[T] = chain.append(item)
 
@@ -378,6 +376,7 @@ object asmGenerator {
     }
 
     assert(stack.size == stackSizeStart + 1)
+    chain ++= zeroRest(MemLocation(stack.head.pointer, Q64), expr.ty.size)
     chain
   }
 
@@ -419,7 +418,7 @@ object asmGenerator {
 
     chain += Compare(destX, stack.head)
     chain += Set(Register(B8, AX), cond)
-    chain += And(RAX, ImmediateVal(_8_BIT_MASK))
+    chain ++= zeroRest(RAX, B8)
     chain += stack.drop()
     chain += stack.push(B8, RAX)
 
@@ -442,6 +441,10 @@ object asmGenerator {
   }
 
   private def stackAlign: AsmLine = And(Register(Q64, SP), ImmediateVal(-16))
+  private def zeroRest(dest: Dest, size: Size): Chain[AsmLine] = size match {
+    case Q64 | D32 => Chain.empty
+    case _         => Chain.one(And(dest, ImmediateVal((1 << (size.toInt * 8)) - 1)))
+  }
 
   private val escapedCharsMapping = escapedChars.map { case (k, v) => v -> s"\\$k" }
   extension (s: String) {
diff --git a/src/test/wacc/examples.scala b/src/test/wacc/examples.scala
index 87def2a..988a6d0 100644
--- a/src/test/wacc/examples.scala
+++ b/src/test/wacc/examples.scala
@@ -93,14 +93,13 @@ class ParallelExamplesSpec extends AnyFlatSpec with BeforeAndAfterAll {
       "^.*wacc-examples/valid/function/nested_functions.*$",
       "^.*wacc-examples/valid/function/simple_functions.*$",
       // "^.*wacc-examples/valid/if.*$",
-      "^.*wacc-examples/valid/IO/print.*$",
+      // "^.*wacc-examples/valid/IO/print.*$",
       // "^.*wacc-examples/valid/IO/read.*$",
       "^.*wacc-examples/valid/IO/IOLoop.wacc.*$",
       // "^.*wacc-examples/valid/IO/IOSequence.wacc.*$",
-      "^.*wacc-examples/valid/pairs.*$",
+      // "^.*wacc-examples/valid/pairs.*$",
       "^.*wacc-examples/valid/runtimeErr.*$",
       // "^.*wacc-examples/valid/scope.*$",
-      "^.*wacc-examples/valid/scope/printAllTypes.wacc$", // while we still don't have arrays implemented
       // "^.*wacc-examples/valid/sequence.*$",
       // "^.*wacc-examples/valid/variables.*$",
       // "^.*wacc-examples/valid/while.*$",