Backport FunPtr

Helps keep functions alive via ptr only (no calls).
A few RISC 5 TFP encoding fixes.

5 files changed, 85 insertions, 2 deletions

diff --git a/chapter22/src/test/java/com/seaofnodes/simple/Chapter18Test.java b/chapter22/src/test/java/com/seaofnodes/simple/Chapter18Test.java
index 7863237e..7cd2831a 100644
--- a/chapter22/src/test/java/com/seaofnodes/simple/Chapter18Test.java
+++ b/chapter22/src/test/java/com/seaofnodes/simple/Chapter18Test.java
@@ -187,7 +187,7 @@ var fcn = arg ? { int x -> x*x; } : { int x -> x+x; };
 return fcn(3);
 """);
         code.parse().opto();
-        assertEquals("Stop[ return (Parm_x($fun2,int,3)<<1); return (Parm_x($fun1,int,3)*x); return #2; ]", code._stop.toString());
+        assertEquals("Stop[ return (Parm_x($fun2,int,3)<<1); return #2; return (Parm_x($fun1,int,3)*x); ]", code._stop.toString());
         assertEquals("6", Eval2.eval(code, 0));
         assertEquals("9", Eval2.eval(code, 1));
     }
diff --git a/chapter22/src/test/java/com/seaofnodes/simple/Chapter19Test.java b/chapter22/src/test/java/com/seaofnodes/simple/Chapter19Test.java
index 007e50b4..7ae094ad 100644
--- a/chapter22/src/test/java/com/seaofnodes/simple/Chapter19Test.java
+++ b/chapter22/src/test/java/com/seaofnodes/simple/Chapter19Test.java
@@ -47,7 +47,7 @@ return 0;
     public void testString() throws IOException {
         String src = Files.readString(Path.of("src/test/java/com/seaofnodes/simple/progs/stringHash.smp"));
         CodeGen code = new CodeGen(src).parse().opto().typeCheck().GCM().localSched();
-        assertEquals("Stop[ return Phi(Region,1,0,0,1); return Phi(Region,._hashCode,Phi(Region,123456789,Phi(Loop,0,(.[]+((Phi_hash<<5)-Phi_hash))))); ]", code._stop.toString());
+        assertEquals("Stop[ return Phi(Region,._hashCode,Phi(Region,123456789,Phi(Loop,0,(.[]+((Phi_hash<<5)-Phi_hash))))); return Phi(Region,1,0,0,1); ]", code._stop.toString());
         //assertEquals("-4898613127354160978", Eval2.eval(code,  2));
     }
 
diff --git a/chapter22/src/test/java/com/seaofnodes/simple/Chapter21Test.java b/chapter22/src/test/java/com/seaofnodes/simple/Chapter21Test.java
index 9f680807..9f901dc2 100644
--- a/chapter22/src/test/java/com/seaofnodes/simple/Chapter21Test.java
+++ b/chapter22/src/test/java/com/seaofnodes/simple/Chapter21Test.java
@@ -12,6 +12,27 @@ import org.junit.Test;
 import static org.junit.Assert.*;
 
 public class Chapter21Test {
+    @Test public void testReturnedFunctionEncoding() throws IOException {
+        String src = "if(arg) return {->42;}; return {->43;};";
+        CodeGen code = new CodeGen(src).driver("riscv","SystemV",null);
+        for( int arg : new int[]{0,1} ) {
+            byte[] image = new byte[1<<16];
+            byte[] bits = code._encoding.bits();
+            System.arraycopy(bits,0,image,0,bits.length);
+            EvalRisc5 cpu = new EvalRisc5(image,1<<15);
+            cpu._pc = code._encoding._opStart[code.link(code._main)._nid];
+            cpu.regs[riscv.A0] = arg;
+            assertEquals(0,cpu.step(100));
+            assertEquals(0,cpu._pc);
+            cpu._pc = (int)cpu.regs[riscv.A0];
+            assertEquals(0,cpu.step(100));
+            assertEquals(0,cpu._pc);
+            assertEquals(arg==0 ? 43 : 42,cpu.regs[riscv.A0]);
+        }
+        // Anonymous bodies need code, but no exported ELF name.
+        new CodeGen(src).driver(TestC.CPU_PORT,TestC.CALL_CONVENTION,"build/objs/anonymous.o");
+    }
+
     @Test public void testArmFloatMemory() throws IOException {
         for( String type : new String[]{"f32","f64"} ) {
             String src = type+"[] !a=new "+type+"[3]; a[arg]=1.25; return a[1];";
diff --git a/chapter22/src/test/java/com/seaofnodes/simple/Chapter22Test.java b/chapter22/src/test/java/com/seaofnodes/simple/Chapter22Test.java
index 60917773..b61e972f 100644
--- a/chapter22/src/test/java/com/seaofnodes/simple/Chapter22Test.java
+++ b/chapter22/src/test/java/com/seaofnodes/simple/Chapter22Test.java
@@ -14,6 +14,53 @@ import static org.junit.Assert.*;
 
 public class Chapter22Test {
 
+    @Test public void testReturnedFunctions() throws IOException {
+        for( String src : new String[]{"return {->42;};", "val f={->42;}; return f;", "return sys.io.p;"} )
+            for( String target : new String[]{"riscv","arm"} ) {
+                CodeGen code = new CheckedCodeGen(src).driver(CodeGen.Phase.Encoding,target,"SystemV").exportELF(null);
+                byte[] image = new byte[1<<16];
+                byte[] bits = code._encoding.bits();
+                System.arraycopy(bits,0,image,0,bits.length);
+                boolean library = src.contains("sys.io.p");
+                // u8[]: four-byte length followed by its bytes.
+                image[0x2000]=2; image[0x2004]='o'; image[0x2005]='k';
+                int entry = code._encoding._opStart[code.link(code._main)._nid];
+                if( target.equals("riscv") ) {
+                    EvalRisc5 cpu = new EvalRisc5(image,1<<15);
+                    cpu._pc = entry;
+                    assertEquals(0,cpu.step(1000));
+                    assertEquals(0,cpu._pc);
+                    cpu._pc = (int)cpu.regs[riscv.A0]; // Call the returned address.
+                    cpu.regs[riscv.A0] = 0x2000;
+                    assertEquals(0,cpu.step(1000));
+                    assertEquals(0,cpu._pc);
+                    if( library ) assertEquals("ok",cpu._stdout.toString());
+                    else assertEquals(42,cpu.regs[riscv.A0]);
+                } else {
+                    EvalArm64 cpu = new EvalArm64(image,1<<15);
+                    cpu._pc = entry;
+                    assertEquals(0,cpu.step(1000));
+                    assertEquals(0,cpu._pc);
+                    cpu._pc = (int)cpu.regs[0];
+                    cpu.regs[0] = 0x2000;
+                    assertEquals(0,cpu.step(1000));
+                    assertEquals(0,cpu._pc);
+                    if( library ) assertEquals("ok",cpu._stdout.toString());
+                    else assertEquals(42,cpu.regs[0]);
+                }
+            }
+        CodeGen unused = new CodeGen("({->42;}); return 0;").parse().opto();
+        assertEquals(1,unused._stop.nIns());
+    }
+
+    @Test public void testReturnedFunctionsNative() throws IOException {
+        String src = "val factory={int x -> if(x) return {->42;}; return {->43;};}; val printer={->return sys.io.p;};";
+        String obj = "build/objs/funptr.o";
+        new CheckedCodeGen(src).driver(TestC.CPU_PORT,TestC.CALL_CONVENTION,obj);
+        assertEquals("ok",TestC.gcc(obj,"","src/test/java/com/seaofnodes/simple/progs/funptr.c",false,
+                                   "build/objs/funptr"+(TestC.OS.startsWith("Windows") ? ".exe" : "")));
+    }
+
     @Test public void testRiscvRightShifts() {
         // SRAI, SRLI, SRA, SRL: a0 = -32 shifted by 4.
         int[] ops = {0x40455513,0x00455513,0x40b55533,0x00b55533};
diff --git a/chapter22/src/test/java/com/seaofnodes/simple/progs/funptr.c b/chapter22/src/test/java/com/seaofnodes/simple/progs/funptr.c
new file mode 100644
index 00000000..7545992d
--- /dev/null
+++ b/chapter22/src/test/java/com/seaofnodes/simple/progs/funptr.c
@@ -0,0 +1,15 @@
+#include <assert.h>
+#include <stdint.h>
+
+typedef int64_t (*Function)(void);
+typedef int64_t (*Printer)(void *);
+extern Function factory(int64_t);
+extern Printer printer(void);
+
+int main(void) {
+    assert(factory(1)() == 42);
+    assert(factory(0)() == 43);
+    struct { uint32_t length; char data[2]; } text = {2, {'o','k'}};
+    printer()(&text);
+    return 0;
+}