From a2a92e5e91c8c9555e0590185a5a7e37702d0c1b Mon Sep 17 00:00:00 2001
From: Rui Ueyama <ruiu@cs.stanford.edu>
Date: Thu, 27 Aug 2020 22:47:31 +0900
Subject: [PATCH] Allow to define a function that takes/returns flonums

---
 codegen.c       | 22 +++++++++++++++++++---
 test/function.c | 11 +++++++++++
 2 files changed, 30 insertions(+), 3 deletions(-)

diff --git a/codegen.c b/codegen.c
index ec48c2c..af4f85b 100644
--- a/codegen.c
+++ b/codegen.c
@@ -714,6 +714,18 @@ static void emit_data(Var *prog) {
   }
 }
 
+static void store_fp(int r, int offset, int sz) {
+  switch (sz) {
+  case 4:
+    println("  movss %%xmm%d, %d(%%rbp)", r, offset);
+    return;
+  case 8:
+    println("  movsd %%xmm%d, %d(%%rbp)", r, offset);
+    return;
+  }
+  unreachable();
+}
+
 static void store_gp(int r, int offset, int sz) {
   switch (sz) {
   case 1:
@@ -782,9 +794,13 @@ static void emit_text(Var *prog) {
     }
 
     // Save passed-by-register arguments to the stack
-    int i = 0;
-    for (Var *var = fn->params; var; var = var->next)
-      store_gp(i++, var->offset, var->ty->size);
+    int gp = 0, fp = 0;
+    for (Var *var = fn->params; var; var = var->next) {
+      if (is_flonum(var->ty))
+        store_fp(fp++, var->offset, var->ty->size);
+      else
+        store_gp(gp++, var->offset, var->ty->size);
+    }
 
     // Emit code
     gen_stmt(fn->body);
diff --git a/test/function.c b/test/function.c
index 450531b..df271a2 100644
--- a/test/function.c
+++ b/test/function.c
@@ -100,6 +100,14 @@ char *fmt(char *buf, char *fmt, ...) {
 double add_double(double x, double y);
 float add_float(float x, float y);
 
+float add_float3(float x, float y, float z) {
+  return x + y + z;
+}
+
+double add_double3(double x, double y, double z) {
+  return x + y + z;
+}
+
 int main() {
   ASSERT(3, ret3());
   ASSERT(8, add2(3, 5));
@@ -163,6 +171,9 @@ int main() {
   ASSERT(6, add_float(2.3, 3.8));
   ASSERT(6, add_double(2.3, 3.8));
 
+  ASSERT(7, add_float3(2.5, 2.5, 2.5));
+  ASSERT(7, add_double3(2.5, 2.5, 2.5));
+
   printf("OK\n");
   return 0;
 }
-- 
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