Give a function a frame where it copies a struct argument

Test/Expect/cexec10.txt

@@ -0,0 +1,2 @@
+4200 0
+600 0

Test/Expect/stest184.pasm

@@ -11,6 +11,9 @@ _fetch_ret
 	ret
 
 _fetchv
+	wrlong	fp, sp
+	add	sp, #4
+	mov	fp, sp
 	mov	arg01, sp
 	add	sp, #20
 	mov	arg02, ptr__dat__
@@ -41,9 +44,14 @@ LR__0004
 LR__0005
 	add	result1, #12
 	rdlong	result1, result1
+	mov	sp, fp
+	sub	sp, #4
+	rdlong	fp, sp
 _fetchv_ret
 	ret
 
+fp
+	long	0
 ptr__dat__
 	long	@@@_dat_
 result1

Test/cexec10.c

@@ -0,0 +1,63 @@
+//
+// a function with no frame of its own that passes a struct on must give
+// back the stack it takes for the copy of the argument
+//
+#include <stdio.h>
+#include <propeller.h>
+
+void myexit(int n)
+{
+    putchar(0xff);
+    putchar(0x0);
+    putchar(n);
+    waitcnt(getcnt() + 40000000);
+#ifdef __OUTPUT_BYTECODE__
+    _cogstop(_cogid());
+#else
+    __asm {
+        cogid n
+        cogstop n
+    }
+#endif    
+}
+
+#ifdef __OUTPUT_BYTECODE__
+// the bytecode backends pass such a struct their own way, which is not
+// what this test is about
+void main() {
+    printf("4200 0\n600 0\n");
+    myexit(0);
+}
+#else
+typedef struct { long long a; int b; } T;
+typedef struct { int a, b, c, d, e; } W;
+
+// a frame of their own: a local array
+int use(T t) { volatile int w[2]; w[0] = (int)t.a; w[1] = t.b; return w[0] + w[1]; }
+int usew(W t) { volatile int w[1]; w[0] = t.a + t.e; return w[0]; }
+
+// no frame: nothing of their own but passing the struct on
+int fwd(T t) { return use(t); }
+int fwdw(W t) { return usew(t); }
+
+// the address of its local is the stack pointer where it is called, called
+// through a pointer so that it is not inlined
+int sp0(void) { volatile int x = 0; return (int)&x; }
+int (*volatile sp)(void) = sp0;
+
+void main() {
+    T t = {40, 2};
+    W w = {1, 2, 3, 4, 5};
+    int m = 0, n = 0;
+    int s0, s1, s2;
+    int i;
+
+    s0 = sp();
+    for (i = 0; i < 100; i++) m += fwd(t);
+    s1 = sp();
+    for (i = 0; i < 100; i++) n += fwdw(w);
+    s2 = sp();
+    printf("%d %d\n%d %d\n", m, s1 - s0, n, s2 - s1);
+    myexit(0);
+}
+#endif

functions.c

@@ -3618,6 +3618,9 @@ AstFuncTempMemory(unsigned siz)
         return NULL;
     }
     val = NewAST(AST_ALLOCA, ast_type_ptr_void, AstInteger(siz));
+    // the memory is given back where the function returns, which a function
+    // without a frame does not do
+    curfunc->uses_alloca = 1;
     ptr = AstTempLocalVariable("_tempptr_", NULL);
     val = AstAssign(ptr, val);
     val = NewAST(AST_STMTLIST, val, curfunc->body);