From c42f6ea184f31f43dd15db76c9f3577d8a1ad97c Mon Sep 17 00:00:00 2001
From: Lioncash <mathew1800@gmail.com>
Date: Fri, 5 Oct 2018 18:00:15 -0400
Subject: [PATCH] constant_propagation_pass: Fold ZeroExtend{Type}ToLong
 opcodes if possible

These are equivalent to the ZeroExtendXToWord variants, so we can
trivially do this as well.
---
 src/ir_opt/constant_propagation_pass.cpp | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/src/ir_opt/constant_propagation_pass.cpp b/src/ir_opt/constant_propagation_pass.cpp
index 6cab7fc4..037f522e 100644
--- a/src/ir_opt/constant_propagation_pass.cpp
+++ b/src/ir_opt/constant_propagation_pass.cpp
@@ -122,6 +122,15 @@ void FoldZeroExtendXToWord(IR::Inst& inst) {
     const u64 value = inst.GetArg(0).GetImmediateAsU64();
     inst.ReplaceUsesWith(IR::Value{static_cast<u32>(value)});
 }
+
+void FoldZeroExtendXToLong(IR::Inst& inst) {
+    if (!inst.AreAllArgsImmediates()) {
+        return;
+    }
+
+    const u64 value = inst.GetArg(0).GetImmediateAsU64();
+    inst.ReplaceUsesWith(IR::Value{value});
+}
 } // Anonymous namespace
 
 void ConstantPropagation(IR::Block& block) {
@@ -167,6 +176,11 @@ void ConstantPropagation(IR::Block& block) {
         case IR::Opcode::ZeroExtendHalfToWord:
             FoldZeroExtendXToWord(inst);
             break;
+        case IR::Opcode::ZeroExtendByteToLong:
+        case IR::Opcode::ZeroExtendHalfToLong:
+        case IR::Opcode::ZeroExtendWordToLong:
+            FoldZeroExtendXToLong(inst);
+            break;
         default:
             break;
         }