[PATCH] D57277: [COFF, ARM64] Don't put jump table into a separate COFF section for EK_LabelDifference32

[Tom Tan via Phabricator via llvm-commits]

TomTan created this revision.
TomTan added a reviewer: eli.friedman.
Herald added subscribers: llvm-commits, kristof.beyls, javed.absar.

Windows ARM64 has PIC relocation model and uses jump table kind
EK_LabelDifference32. This produces jump table entry as
".word LBB123 - LJTI1_2" if the jump table is not compressed (
such as in debug build). This jump table entry represents the
distance between the block and jump table. There is no relocation
type for linker to do fixup for this entry correctly if they are
in different COFF section. This conforms to the implementation of
EmitJumpTableInfo from parent class.


Repository:
  rL LLVM

https://reviews.llvm.org/D57277

Files:
  lib/Target/AArch64/AArch64AsmPrinter.cpp
  lib/Target/AArch64/AArch64TargetMachine.cpp
  test/CodeGen/AArch64/win64-jumptable.ll


Index: test/CodeGen/AArch64/win64-jumptable.ll
===================================================================
--- /dev/null
+++ test/CodeGen/AArch64/win64-jumptable.ll
@@ -0,0 +1,48 @@
+; RUN: llc -o - %s -mtriple=aarch64-windows -aarch64-enable-compress-jump-tables=0 | FileCheck %s
+
+define void @f(i32 %x) {
+entry:
+  switch i32 %x, label %sw.epilog [
+    i32 0, label %sw.bb
+    i32 1, label %sw.bb1
+    i32 2, label %sw.bb2
+    i32 3, label %sw.bb3
+  ]
+
+sw.bb:                                            ; preds = %entry
+  tail call void @g(i32 0) #2
+  br label %sw.epilog
+
+sw.bb1:                                           ; preds = %entry
+  tail call void @g(i32 1) #2
+  br label %sw.epilog
+
+sw.bb2:                                           ; preds = %entry
+  tail call void @g(i32 2) #2
+  br label %sw.epilog
+
+sw.bb3:                                           ; preds = %entry
+  tail call void @g(i32 3) #2
+  br label %sw.epilog
+
+sw.epilog:                                        ; preds = %entry, %sw.bb3, %sw.bb2, %sw.bb1, %sw.bb
+  tail call void @g(i32 10) #2
+  ret void
+}
+
+declare void @g(i32)
+
+; CHECK:		.text
+; CHECK:		f:
+; CHECK:		.seh_proc f
+; CHECK:		b	g
+; CHECK-NEXT:	.p2align	2
+; CHECK:		.LJTI0_0:
+; CHECK:		.word	.LBB0_2-.LJTI0_0
+; CHECK:		.word	.LBB0_3-.LJTI0_0
+; CHECK:		.word	.LBB0_4-.LJTI0_0
+; CHECK:		.word	.LBB0_5-.LJTI0_0
+; CHECK:		.section	.xdata,"dr"
+; CHECK:		.seh_handlerdata
+; CHECK:		.text
+; CHECK:		.seh_endproc
Index: lib/Target/AArch64/AArch64TargetMachine.cpp
===================================================================
--- lib/Target/AArch64/AArch64TargetMachine.cpp
+++ lib/Target/AArch64/AArch64TargetMachine.cpp
@@ -210,4 +210,4 @@
                                            Optional<Reloc::Model> RM) {
-  // AArch64 Darwin is always PIC.
-  if (TT.isOSDarwin())
+  // AArch64 Darwin and Windows are always PIC.
+  if (TT.isOSDarwin() || TT.isOSWindows())
     return Reloc::PIC_;
Index: lib/Target/AArch64/AArch64AsmPrinter.cpp
===================================================================
--- lib/Target/AArch64/AArch64AsmPrinter.cpp
+++ lib/Target/AArch64/AArch64AsmPrinter.cpp
@@ -580,5 +580,12 @@
 
+  const Function &F = MF->getFunction();
   const TargetLoweringObjectFile &TLOF = getObjFileLowering();
-  MCSection *ReadOnlySec = TLOF.getSectionForJumpTable(MF->getFunction(), TM);
-  OutStreamer->SwitchSection(ReadOnlySec);
+  bool JTInDiffSection = !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);
+  }
 


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