From f5e6fbac24f198d075a7c4bc0879426e79040bcf Mon Sep 17 00:00:00 2001
From: =?utf8?q?Martin=20Storsj=C3=B6?= <martin@martin.st>
Date: Tue, 4 Aug 2020 14:41:48 +0300
Subject: [PATCH] [AArch64] [Windows] Error out on unsupported symbol locations

These might occur in seemingly generic assembly. Previously when
targeting COFF, they were silently ignored, which certainly won't
give the right result. Instead clearly error out, to make it clear
that the assembly needs to be adjusted for this target.

Also change a preexisting report_fatal_error into a proper error
message, pointing out the offending source instruction. This isn't
strictly an internal error, as it can be triggered by user input.

Differential Revision: https://reviews.llvm.org/D85242
---
 .../MCTargetDesc/AArch64WinCOFFObjectWriter.cpp    | 28 +++++++++++++-
 llvm/test/MC/AArch64/coff-relocations-diags.s      | 43 ++++++++++++++++++++++
 2 files changed, 69 insertions(+), 2 deletions(-)
 create mode 100644 llvm/test/MC/AArch64/coff-relocations-diags.s

diff --git a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64WinCOFFObjectWriter.cpp b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64WinCOFFObjectWriter.cpp
index aa50bd05..aaadc8d 100644
--- a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64WinCOFFObjectWriter.cpp
+++ b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64WinCOFFObjectWriter.cpp
@@ -11,6 +11,7 @@
 #include "llvm/ADT/Twine.h"
 #include "llvm/BinaryFormat/COFF.h"
 #include "llvm/MC/MCAsmBackend.h"
+#include "llvm/MC/MCContext.h"
 #include "llvm/MC/MCExpr.h"
 #include "llvm/MC/MCFixup.h"
 #include "llvm/MC/MCFixupKindInfo.h"
@@ -48,10 +49,33 @@ unsigned AArch64WinCOFFObjectWriter::getRelocType(
                                       : Target.getSymA()->getKind();
   const MCExpr *Expr = Fixup.getValue();
 
+  if (const AArch64MCExpr *A64E = dyn_cast<AArch64MCExpr>(Expr)) {
+    AArch64MCExpr::VariantKind RefKind = A64E->getKind();
+    switch (AArch64MCExpr::getSymbolLoc(RefKind)) {
+    case AArch64MCExpr::VK_ABS:
+    case AArch64MCExpr::VK_SECREL:
+      // Supported
+      break;
+    default:
+      Ctx.reportError(Fixup.getLoc(), "relocation variant " +
+                                          A64E->getVariantKindName() +
+                                          " unsupported on COFF targets");
+      return COFF::IMAGE_REL_ARM64_ABSOLUTE; // Dummy return value
+    }
+  }
+
   switch (static_cast<unsigned>(Fixup.getKind())) {
   default: {
-    const MCFixupKindInfo &Info = MAB.getFixupKindInfo(Fixup.getKind());
-    report_fatal_error(Twine("unsupported relocation type: ") + Info.Name);
+    if (const AArch64MCExpr *A64E = dyn_cast<AArch64MCExpr>(Expr)) {
+      Ctx.reportError(Fixup.getLoc(), "relocation type " +
+                                          A64E->getVariantKindName() +
+                                          " unsupported on COFF targets");
+    } else {
+      const MCFixupKindInfo &Info = MAB.getFixupKindInfo(Fixup.getKind());
+      Ctx.reportError(Fixup.getLoc(), Twine("relocation type ") + Info.Name +
+                                          " unsupported on COFF targets");
+    }
+    return COFF::IMAGE_REL_ARM64_ABSOLUTE; // Dummy return value
   }
 
   case FK_Data_4:
diff --git a/llvm/test/MC/AArch64/coff-relocations-diags.s b/llvm/test/MC/AArch64/coff-relocations-diags.s
new file mode 100644
index 0000000..24869ce
--- /dev/null
+++ b/llvm/test/MC/AArch64/coff-relocations-diags.s
@@ -0,0 +1,43 @@
+// RUN: not llvm-mc -triple aarch64-win32 -filetype=obj %s -o /dev/null 2>&1 | FileCheck %s
+
+  adrp x0, :got:symbol
+  // CHECK: error: relocation variant :got: unsupported on COFF targets
+  // CHECK-NEXT: adrp x0, :got:symbol
+  // CHECK-NEXT: ^
+
+  ldr x0, [x0, :got_lo12:symbol]
+  // CHECK: error: relocation variant :got_lo12: unsupported on COFF targets
+  // CHECK-NEXT: ldr x0, [x0, :got_lo12:symbol]
+  // CHECK-NEXT: ^
+
+  adrp x0, :tlsdesc:symbol
+  // CHECK: error: relocation variant :tlsdesc: unsupported on COFF targets
+  // CHECK-NEXT: adrp x0, :tlsdesc:symbol
+  // CHECK-NEXT: ^
+  add x0, x0, :tlsdesc_lo12:symbol
+  // CHECK: error: relocation variant :tlsdesc_lo12: unsupported on COFF targets
+  // CHECK-NEXT: add x0, x0, :tlsdesc_lo12:symbol
+  // CHECK-NEXT: ^
+
+  adrp x0, :gottprel:symbol
+  // CHECK: error: relocation variant :gottprel: unsupported on COFF targets
+  // CHECK-NEXT: adrp x0, :gottprel:symbol
+  // CHECK-NEXT: ^
+  ldr x0, [x0, :gottprel_lo12:symbol]
+  // CHECK: error: relocation variant :gottprel_lo12: unsupported on COFF targets
+  // CHECK-NEXT: ldr x0, [x0, :gottprel_lo12:symbol]
+  // CHECK-NEXT: ^
+
+  add x0, x0, #:dtprel_hi12:symbol, lsl #12
+  // CHECK: error: relocation variant :dtprel_hi12: unsupported on COFF targets
+  // CHECK-NEXT: add x0, x0, #:dtprel_hi12:symbol, lsl #12
+  // CHECK-NEXT: ^
+  add x0, x0, :dtprel_lo12:symbol
+  // CHECK: error: relocation variant :dtprel_lo12: unsupported on COFF targets
+  // CHECK-NEXT: add x0, x0, :dtprel_lo12:symbol
+  // CHECK-NEXT: ^
+
+  movz x0, #:abs_g0:symbol
+  // CHECK: error: relocation type :abs_g0: unsupported on COFF targets
+  // CHECK-NEXT: movz x0, #:abs_g0:symbol
+  // CHECK-NEXT: ^
-- 
2.7.4