optimise freeing the stack frame

callisto-lang · Jun 8, 2024 · 3aa906d · 3aa906d
1 parent ce74b8c
commit 3aa906d
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Showing 3 changed files with 38 additions and 6 deletions.
diff --git a/source/backends/linux86.d b/source/backends/linux86.d
@@ -362,7 +362,12 @@ class BackendLinux86 : CompilerBackend {
 			foreach (ref var ; variables) {
 				scopeSize += var.Size();
 			}
-			output ~= format("add rsp, %d\n", scopeSize);
+			if (scopeSize == 1) {
+				output ~= "inc rsp\n";
+			}
+			else if (scopeSize > 0) {
+				output ~= format("add rsp, %d\n", scopeSize);
+			}
 
 			output    ~= "ret\n";
 			//output    ~= format("__func_end__%s:\n", node.name.Sanitise());
@@ -652,7 +657,13 @@ class BackendLinux86 : CompilerBackend {
 		foreach (ref var ; variables) {
 			scopeSize += var.Size();
 		}
-		output ~= format("add rsp, %d\n", scopeSize);
+		if (scopeSize == 1) {
+			output ~= "inc rsp\n";
+		}
+		else if (scopeSize > 0) {
+			output ~= format("add rsp, %d\n", scopeSize);
+		}
+
 		output ~= "ret\n";
 	}
 

diff --git a/source/backends/rm86.d b/source/backends/rm86.d
@@ -268,7 +268,12 @@ class BackendRM86 : CompilerBackend {
 			foreach (ref var ; variables) {
 				scopeSize += var.Size();
 			}
-			output ~= format("add sp, %d\n", scopeSize);
+			if (scopeSize == 1) {
+				output ~= "inc sp\n";
+			}
+			else {
+				output ~= format("add sp, %d\n", scopeSize);
+			}
 
 			output    ~= "ret\n";
 			//output    ~= format("__func_end__%s:\n", node.name.Sanitise());
@@ -565,8 +570,12 @@ class BackendRM86 : CompilerBackend {
 		foreach (ref var ; variables) {
 			scopeSize += var.Size();
 		}
-		output ~= format("add sp, %d\n", scopeSize);
-		output ~= "ret\n";
+		if (scopeSize == 1) {
+			output ~= "inc sp\n";
+		}
+		else {
+			output ~= format("add sp, %d\n", scopeSize);
+		}
 	}
 
 	override void CompileConst(ConstNode node) {

diff --git a/source/backends/uxn.d b/source/backends/uxn.d
@@ -268,7 +268,19 @@ class BackendUXN : CompilerBackend {
 			foreach (ref var ; variables) {
 				scopeSize += var.Size();
 			}
-			output ~= format(".vsp LDZ2 #%.4x ADD2 .vsp STZ2\n", scopeSize);
+			//output ~= format(".vsp LDZ2 #%.4x ADD2 .vsp STZ2\n", scopeSize);
+			if (scopeSize > 0) {
+				output ~= ".vsp LDZ2 ";
+
+				switch (scopeSize) {
+					case 1:  output ~= "INC2 "; break;
+					case 2:  output ~= "INC2 INC2 "; break;
+					case 3:  output ~= "INC2 INC2 INC2 "; break;
+					default: output ~= format("#%.4x ADD2 ", scopeSize); break;
+				}
+
+				output ~= ".vsp STZ2\n";
+			}
 
 			output    ~= "JMP2r\n";
 			variables  = [];