[MC] [AArch64] Correctly resolve ":abs_g1:3" etc.

We have to treat constructs like this as if they were "symbolic", to use
the correct codepath to resolve them.  This mostly only affects movz
etc. because the other uses of classifySymbolRef conservatively treat
everything that isn't a constant as if it were a symbol.

Differential Revision: https://reviews.llvm.org/D55906

llvm-svn: 349800

llvm/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp

@@ -5434,10 +5434,16 @@ AArch64AsmParser::classifySymbolRef(const MCExpr *Expr,
   // Check that it looks like a symbol + an addend
   MCValue Res;
   bool Relocatable = Expr->evaluateAsRelocatable(Res, nullptr, nullptr);
-  if (!Relocatable || !Res.getSymA() || Res.getSymB())
+  if (!Relocatable || Res.getSymB())
     return false;
 
-  DarwinRefKind = Res.getSymA()->getKind();
+  // Treat expressions with an ELFRefKind (like ":abs_g1:3", or
+  // ":abs_g1:x" where x is constant) as symbolic even if there is no symbol.
+  if (!Res.getSymA() && ELFRefKind == AArch64MCExpr::VK_INVALID)
+    return false;
+
+  if (Res.getSymA())
+    DarwinRefKind = Res.getSymA()->getKind();
   Addend = Res.getConstant();
 
   // It's some symbol reference + a constant addend, but really

llvm/test/MC/AArch64/fixup-absolute.s

@@ -1,21 +1,40 @@
 // RUN: llvm-mc -triple aarch64--none-eabi -filetype obj < %s -o - | llvm-objdump -d - | FileCheck %s
 
+onepart_before = 0x1234
+twopart_before = 0x12345678
+threepart_before = 0x1234567890AB
+fourpart_before = 0x1234567890ABCDEF
+
+// CHECK: mov     x0, #1311673391471656960
 // CHECK: mov     x0, #1311673391471656960
-movz x0, #:abs_g3:fourpart
+movz x0, #:abs_g3:fourpart_before
+movz x0, #:abs_g3:fourpart_after
 // CHECK: mov     x0, #20014547599360
-movz x0, #:abs_g2:threepart
+// CHECK: mov     x0, #20014547599360
+movz x0, #:abs_g2:threepart_before
+movz x0, #:abs_g2:threepart_after
+// CHECK: movk    x0, #22136, lsl #32
 // CHECK: movk    x0, #22136, lsl #32
-movk x0, #:abs_g2_nc:fourpart
+movk x0, #:abs_g2_nc:fourpart_before
+movk x0, #:abs_g2_nc:fourpart_after
 // CHECK: mov     x0, #305397760
-movz x0, #:abs_g1:twopart
+// CHECK: mov     x0, #305397760
+movz x0, #:abs_g1:twopart_before
+movz x0, #:abs_g1:twopart_after
+// CHECK: movk    x0, #37035, lsl #16
 // CHECK: movk    x0, #37035, lsl #16
-movk x0, #:abs_g1_nc:fourpart
+movk x0, #:abs_g1_nc:fourpart_before
+movk x0, #:abs_g1_nc:fourpart_after
 // CHECK: mov     x0, #4660
-movz x0, #:abs_g0:onepart
+// CHECK: mov     x0, #4660
+movz x0, #:abs_g0:onepart_before
+movz x0, #:abs_g0:onepart_after
+// CHECK: movk    x0, #52719
 // CHECK: movk    x0, #52719
-movk x0, #:abs_g0_nc:fourpart
+movk x0, #:abs_g0_nc:fourpart_before
+movk x0, #:abs_g0_nc:fourpart_after
 
-onepart = 0x1234
-twopart = 0x12345678
-threepart = 0x1234567890AB
-fourpart = 0x1234567890ABCDEF
+onepart_after = 0x1234
+twopart_after = 0x12345678
+threepart_after = 0x1234567890AB
+fourpart_after = 0x1234567890ABCDEF