MIR Gen - Don't emit `If` terminator if known true/false

1 files changed, 12 insertions, 0 deletions

diff --git a/src/mir/from_hir.cpp b/src/mir/from_hir.cpp
index 3aedd680..5a0efc29 100644
--- a/src/mir/from_hir.cpp
+++ b/src/mir/from_hir.cpp
@@ -675,6 +675,18 @@ namespace {
                 }
             }
 
+            if( auto* cond_lit = dynamic_cast<::HIR::ExprNode_Literal*>(cond_p->get()) )
+            {
+                DEBUG("- constant condition");
+                if( cond_lit->m_data.as_Boolean() ) {
+                    m_builder.end_block( ::MIR::Terminator::make_Goto({ true_branch }) );
+                }
+                else {
+                    m_builder.end_block( ::MIR::Terminator::make_Goto({ false_branch }) );
+                }
+                return ;
+            }
+
             // If short-circuiting didn't apply, emit condition
             ::MIR::LValue   decision_val;
             {