[COFF, ARM64] Don't put jump table into a separate COFF section for E…

…K_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 llvm-svn: 352465
llvm · Jan 29, 2019 · f5884d2 · f5884d2
1 parent ee7c61f
commit f5884d2
Showing 3 changed files with 61 additions and 4 deletions.
diff --git a/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp b/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp
@@ -578,9 +578,18 @@ void AArch64AsmPrinter::EmitJumpTableInfo() {
   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) {

diff --git a/llvm/lib/Target/AArch64/AArch64TargetMachine.cpp b/llvm/lib/Target/AArch64/AArch64TargetMachine.cpp
@@ -208,8 +208,8 @@ static std::string computeDataLayout(const Triple &TT,
 
 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

diff --git a/llvm/test/CodeGen/AArch64/win64-jumptable.ll b/llvm/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-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