Backport FunPtr

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

2 files changed, 5 insertions, 11 deletions

diff --git a/chapter21/src/main/java/com/seaofnodes/simple/codegen/ElfFile.java b/chapter21/src/main/java/com/seaofnodes/simple/codegen/ElfFile.java
index 746ecfed..d1d20919 100644
--- a/chapter21/src/main/java/com/seaofnodes/simple/codegen/ElfFile.java
+++ b/chapter21/src/main/java/com/seaofnodes/simple/codegen/ElfFile.java
@@ -221,6 +221,7 @@ public class ElfFile {
                 i++;
             int end = _code._encoding._opStart[ret._nid] + _code._encoding._opLen[ret._nid];
 
+            if( fun._name==null ) continue; // Anonymous addresses are relocated within .text.
             Symbol func = new Symbol(fun._name, text._index, SYM_BIND_GLOBAL, SYM_TYPE_FUNC);
             func._value = _code._encoding._opStart[fun._nid];
             func._size = end - func._value;
diff --git a/chapter21/src/main/java/com/seaofnodes/simple/node/cpus/riscv/TFPRISC.java b/chapter21/src/main/java/com/seaofnodes/simple/node/cpus/riscv/TFPRISC.java
index 17613009..a4355e17 100644
--- a/chapter21/src/main/java/com/seaofnodes/simple/node/cpus/riscv/TFPRISC.java
+++ b/chapter21/src/main/java/com/seaofnodes/simple/node/cpus/riscv/TFPRISC.java
@@ -26,22 +26,15 @@ public class TFPRISC extends ConstantNode implements MachNode, RIPRelSize {
         enc.add4(addi);
     }
 
-    @Override public byte encSize(int delta) {
-        if( -(1L<<11) <= delta && delta < (1L<<11) ) return 4;
-        throw Utils.TODO();
-    }
+    @Override public byte encSize(int delta) { return 8; }
 
     // Delta is from opcode start
     @Override public void patch( Encoding enc, int opStart, int opLen, int delta ) {
         short rpc = enc.reg(this);
         if( opLen==8 ) {
-            // AUIPC (upper 20 bits)
-            // opstart of add
-            int next = opStart + opLen;
-            enc.patch4(opStart,riscv.u_type(riscv.OP_AUIPC, rpc, delta));
-            // addi(low 12 bits)
-            enc.patch4(next,riscv.i_type(riscv.OP_IMM, rpc, 0, rpc, delta & 0xFFF));
-            // addi
+            // ADDI sign-extends its low 12 bits, so round the AUIPC high part.
+            enc.patch4(opStart  ,riscv.u_type(riscv.OP_AUIPC, rpc, (delta+0x800)>>12));
+            enc.patch4(opStart+4,riscv.i_type(riscv.OP_IMM, rpc, 0, rpc, delta & 0xFFF));
         } else {
              // should not happen as one instruction is 4 byte, and TFP arm encodes 2.
             throw Utils.TODO();