[llvm] 4e5488a - [AArch64] [COFF] Move jump tables back to the readonly section

[Martin Storsjö via llvm-commits]

Author: Martin Storsjö
Date: 2021-11-23T10:13:48+02:00
New Revision: 4e5488afb27a64d12a76b770cc86bab8074e9c57

URL: https://github.com/llvm/llvm-project/commit/4e5488afb27a64d12a76b770cc86bab8074e9c57
DIFF: https://github.com/llvm/llvm-project/commit/4e5488afb27a64d12a76b770cc86bab8074e9c57.diff

LOG: [AArch64] [COFF] Move jump tables back to the readonly section

This essentially reverts f5884d255e78305d41c28c6e001a460ff83981d8
(D57277).

That commit was made as a workaround since LLVM back then didn't
support cross-section relative relocations (IMAGE_REL_ARM64_REL32)
in COFF for ARM64. Support for this was implemented later,
in d5c5cf5ce8d921fc8c5e1b608c298a1ffa688d37 (D99572) and
382c505d9cfca8adaec47aea2da7bbcbc00fc05c (D102217).

The commit that moved jump tables to the function section noted
that it woud be ideal to utilize IMAGE_REL_ARM64_REL32.

Differential Revision: https://reviews.llvm.org/D113576

Added: 
    

Modified: 
    llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp
    llvm/test/CodeGen/AArch64/win64-jumptable.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp b/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp
index 9f527a17d390a..aeebb49675b24 100644
--- a/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp
+++ b/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp
@@ -818,18 +818,9 @@ void AArch64AsmPrinter::emitJumpTableInfo() {
   const std::vector<MachineJumpTableEntry> &JT = MJTI->getJumpTables();
   if (JT.empty()) return;
 
-  const Function &F = MF->getFunction();
   const TargetLoweringObjectFile &TLOF = getObjFileLowering();
-  bool JTInDiffSection =
-      !STI->isTargetCOFF() ||
-      !TLOF.shouldPutJumpTableInFunctionSection(
-          MJTI->getEntryKind() == MachineJumpTableInfo::EK_LabelDifference32,
-          F);
-  if (JTInDiffSection) {
-      // Drop it in the readonly section.
-      MCSection *ReadOnlySec = TLOF.getSectionForJumpTable(F, TM);
-      OutStreamer->SwitchSection(ReadOnlySec);
-  }
+  MCSection *ReadOnlySec = TLOF.getSectionForJumpTable(MF->getFunction(), TM);
+  OutStreamer->SwitchSection(ReadOnlySec);
 
   auto AFI = MF->getInfo<AArch64FunctionInfo>();
   for (unsigned JTI = 0, e = JT.size(); JTI != e; ++JTI) {

diff  --git a/llvm/test/CodeGen/AArch64/win64-jumptable.ll b/llvm/test/CodeGen/AArch64/win64-jumptable.ll
index 4c19ee877243d..5de4d79e16f66 100644
--- a/llvm/test/CodeGen/AArch64/win64-jumptable.ll
+++ b/llvm/test/CodeGen/AArch64/win64-jumptable.ll
@@ -38,12 +38,14 @@ declare void @g(i32, i32)
 ; CHECK:    .seh_proc f
 ; CHECK:    b g
 ; CHECK-NEXT:  .seh_endfunclet
+; CHECK-NEXT:  .section .rdata,"dr"
 ; CHECK-NEXT: .p2align  2
 ; CHECK-NEXT: .LJTI0_0:
 ; CHECK:    .word .LBB0_2-.Ltmp0
 ; CHECK:    .word .LBB0_3-.Ltmp0
 ; CHECK:    .word .LBB0_4-.Ltmp0
 ; CHECK:    .word .LBB0_5-.Ltmp0
+; CHECK:    .text
 ; CHECK:    .seh_endproc
 
 ; Check that we can emit an object file with correct unwind info.