[llvm-branch-commits] [llvm] release/18.x: [X86] Resolve FIXME: Enable PC relative calls on Windows (PR #84185)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-x86

Author: AtariDreams (AtariDreams)

<details>
<summary>Changes</summary>

WinCOFFObjectWriter::RecordRelocation has been able to emit PC relative calls for a while now, but the workaround code has not been removed. We can safely enable it now for Windows.

---
Full diff: https://github.com/llvm/llvm-project/pull/84185.diff


2 Files Affected:

- (modified) llvm/lib/Target/X86/X86Subtarget.cpp (+1-4) 
- (modified) llvm/test/CodeGen/X86/call-imm.ll (+3-1) 


``````````diff
diff --git a/llvm/lib/Target/X86/X86Subtarget.cpp b/llvm/lib/Target/X86/X86Subtarget.cpp
index 07f535685e8f97..74d9b1bd327ea1 100644
--- a/llvm/lib/Target/X86/X86Subtarget.cpp
+++ b/llvm/lib/Target/X86/X86Subtarget.cpp
@@ -238,10 +238,7 @@ X86Subtarget::classifyGlobalFunctionReference(const GlobalValue *GV,
 
 /// Return true if the subtarget allows calls to immediate address.
 bool X86Subtarget::isLegalToCallImmediateAddr() const {
-  // FIXME: I386 PE/COFF supports PC relative calls using IMAGE_REL_I386_REL32
-  // but WinCOFFObjectWriter::RecordRelocation cannot emit them.  Once it does,
-  // the following check for Win32 should be removed.
-  if (Is64Bit || isTargetWin32())
+  if (Is64Bit)
     return false;
   return isTargetELF() || TM.getRelocationModel() == Reloc::Static;
 }
diff --git a/llvm/test/CodeGen/X86/call-imm.ll b/llvm/test/CodeGen/X86/call-imm.ll
index b8f5a0cb9b4287..5628dc3faddc08 100644
--- a/llvm/test/CodeGen/X86/call-imm.ll
+++ b/llvm/test/CodeGen/X86/call-imm.ll
@@ -2,6 +2,7 @@
 ; RUN: llc < %s -mtriple=i386-apple-darwin -relocation-model=pic | FileCheck -check-prefix X86PIC %s
 ; RUN: llc < %s -mtriple=i386-pc-linux -relocation-model=dynamic-no-pic | FileCheck -check-prefix X86DYN %s
 ; RUN: llc < %s -mtriple=i386-pc-win32 -relocation-model=static | FileCheck -check-prefix X86WINSTA %s
+; RUN: llc < %s -mtriple=i386-pc-win32 -relocation-model=pic | FileCheck -check-prefix X86WINPIC %s
 
 ; Call to immediate is not safe on x86-64 unless we *know* that the
 ; call will be within 32-bits pcrel from the dest immediate.
@@ -21,5 +22,6 @@ entry:
 ; X86STA: {{call.*12345678}}
 ; X86PIC-NOT: {{call.*12345678}}
 ; X86DYN: {{call.*12345678}}
-; X86WINSTA: {{call.*[*]%eax}}
+; X86WINSTA: {{call.*12345678}}
+; X86WINPIC-NOT: {{call.*12345678}}
 ; X64: {{call.*[*]%rax}}

``````````

</details>


https://github.com/llvm/llvm-project/pull/84185