fix(llvm): R_X86_64_32S addresses did not fit, swapping to PIC code (#130)

Author: martinjrobins

diffsl/src/execution/llvm/codegen.rs

@@ -110,7 +110,7 @@ impl LlvmModule {
                 cpu.as_str(),
                 features.as_str(),
                 inkwell::OptimizationLevel::Aggressive,
-                inkwell::targets::RelocMode::Default,
+                inkwell::targets::RelocMode::PIC,
                 inkwell::targets::CodeModel::Default,
             )
             .unwrap();

diffsl/src/execution/relocations.rs

@@ -149,8 +149,24 @@ fn handle_relocation_generic_x86(rela: &Relocation, s: *const u8, p: *mut u8) ->
         }
     };
     match size {
-        16 => unsafe { (p as *mut i16).write_unaligned(i16::try_from(val).unwrap()) },
-        32 => unsafe { (p as *mut i32).write_unaligned(i32::try_from(val).unwrap()) },
+        16 => unsafe {
+            (p as *mut i16).write_unaligned(i16::try_from(val).map_err(|_| {
+                anyhow!(
+                    "x86 relocation overflow for {:?} {:?}-bit relocation: value {val:#x} does not fit in i16",
+                    rela.kind(),
+                    size
+                )
+            })?)
+        },
+        32 => unsafe {
+            (p as *mut i32).write_unaligned(i32::try_from(val).map_err(|_| {
+                anyhow!(
+                    "x86 relocation overflow for {:?} {:?}-bit relocation: value {val:#x} does not fit in i32",
+                    rela.kind(),
+                    size
+                )
+            })?)
+        },
         64 => unsafe { (p as *mut i64).write_unaligned(val) },
         _ => return Err(anyhow!("Unsupported relocation size {:?}", size)),
     }

diffsl/tests/roundtrips.rs

@@ -8,8 +8,9 @@
 ))]
 fn model_code() -> &'static str {
     r#"
+        c_i { 1.0, 1.0 }
         u { y = 1 }
-        F { -y }
+        F { -y * c_i[N] }
         out { y }
     "#
 }