From a1dbeee062b922e044c859bfb1f227fa568828df Mon Sep 17 00:00:00 2001
From: whitequark <whitequark@whitequark.org>
Date: Tue, 28 Apr 2020 13:11:34 +0000
Subject: [PATCH] Implement X86CallPCRel4 relocations in the JIT linker.

All calls inside a module are relocated with these.
---
 crates/jit/src/link.rs | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/crates/jit/src/link.rs b/crates/jit/src/link.rs
index 770d61ea74..6918b2d4b3 100644
--- a/crates/jit/src/link.rs
+++ b/crates/jit/src/link.rs
@@ -94,9 +94,14 @@ fn apply_reloc(
             write_unaligned(reloc_address as *mut u32, reloc_delta_u32);
         },
         #[cfg(target_pointer_width = "32")]
-        Reloc::X86CallPCRel4 => {
-            // ignore
-        }
+        Reloc::X86CallPCRel4 => unsafe {
+            let reloc_address = body.add(r.offset as usize) as usize;
+            let reloc_addend = r.addend as isize;
+            let reloc_delta_u32 = (target_func_address as u32)
+                .wrapping_sub(reloc_address as u32)
+                .wrapping_add(reloc_addend as u32);
+            write_unaligned(reloc_address as *mut u32, reloc_delta_u32);
+        },
         Reloc::X86PCRelRodata4 => {
             // ignore
         }