[llvm] r352465 - [COFF, ARM64] Don't put jump table into a separate COFF section for EK_LabelDifference32

[Martin Storsjo via llvm-commits]

Author: mstorsjo
Date: Tue Jan 29 01:36:48 2019
New Revision: 352465

URL: http://llvm.org/viewvc/llvm-project?rev=352465&view=rev
Log:
[COFF, ARM64] Don't put jump table into a separate COFF section for EK_LabelDifference32

Windows ARM64 has PIC relocation model and uses jump table kind
EK_LabelDifference32. This produces jump table entry as
".word LBB123 - LJTI1_2" which represents the distance between the block
and jump table.

A new relocation type (IMAGE_REL_ARM64_REL32) is needed to do the fixup
correctly if they are in different COFF section.

This change saves the jump table to the same COFF section as the
associated code. An ideal fix could be utilizing IMAGE_REL_ARM64_REL32
relocation type.

Patch by Tom Tan!

Differential Revision: https://reviews.llvm.org/D57277

Added:
    llvm/trunk/test/CodeGen/AArch64/win64-jumptable.ll
Modified:
    llvm/trunk/lib/Target/AArch64/AArch64AsmPrinter.cpp
    llvm/trunk/lib/Target/AArch64/AArch64TargetMachine.cpp

Modified: llvm/trunk/lib/Target/AArch64/AArch64AsmPrinter.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/AArch64/AArch64AsmPrinter.cpp?rev=352465&r1=352464&r2=352465&view=diff
==============================================================================
--- llvm/trunk/lib/Target/AArch64/AArch64AsmPrinter.cpp (original)
+++ llvm/trunk/lib/Target/AArch64/AArch64AsmPrinter.cpp Tue Jan 29 01:36:48 2019
@@ -578,9 +578,18 @@ void AArch64AsmPrinter::EmitJumpTableInf
   const std::vector<MachineJumpTableEntry> &JT = MJTI->getJumpTables();
   if (JT.empty()) return;
 
+  const Function &F = MF->getFunction();
   const TargetLoweringObjectFile &TLOF = getObjFileLowering();
-  MCSection *ReadOnlySec = TLOF.getSectionForJumpTable(MF->getFunction(), TM);
-  OutStreamer->SwitchSection(ReadOnlySec);
+  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);
+  }
 
   auto AFI = MF->getInfo<AArch64FunctionInfo>();
   for (unsigned JTI = 0, e = JT.size(); JTI != e; ++JTI) {

Modified: llvm/trunk/lib/Target/AArch64/AArch64TargetMachine.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/AArch64/AArch64TargetMachine.cpp?rev=352465&r1=352464&r2=352465&view=diff
==============================================================================
--- llvm/trunk/lib/Target/AArch64/AArch64TargetMachine.cpp (original)
+++ llvm/trunk/lib/Target/AArch64/AArch64TargetMachine.cpp Tue Jan 29 01:36:48 2019
@@ -208,8 +208,8 @@ static std::string computeDataLayout(con
 
 static Reloc::Model getEffectiveRelocModel(const Triple &TT,
                                            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_;
   // On ELF platforms the default static relocation model has a smart enough
   // linker to cope with referencing external symbols defined in a shared

Added: llvm/trunk/test/CodeGen/AArch64/win64-jumptable.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/AArch64/win64-jumptable.ll?rev=352465&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/AArch64/win64-jumptable.ll (added)
+++ llvm/trunk/test/CodeGen/AArch64/win64-jumptable.ll Tue Jan 29 01:36:48 2019
@@ -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-NEXT:	.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