Recommitted fix for PR18931, with extended tests set.

Issue subject: Crash using integrated assembler with immediate arithmetic

Fix description:
Expressions like 'cmp r0, #(l1 - l2) >> 3' could not be evaluated on asm parsing stage,
since it is impossible to resolve labels on this stage. In the end of stage we still have
expression (MCExpr).
Then, when we want to encode it, we expect it to be an immediate, but it still an expression.
Patch introduces a Fixup (MCFixup instance), that is processed after main encoding stage.

llvm-svn: 205094

1 files changed, 19 insertions, 1 deletions

diff --git a/llvm/lib/Target/ARM/MCTargetDesc/ARMMCCodeEmitter.cpp b/llvm/lib/Target/ARM/MCTargetDesc/ARMMCCodeEmitter.cpp
index 12cd33676a8..7ce9104ca7b 100644
--- a/llvm/lib/Target/ARM/MCTargetDesc/ARMMCCodeEmitter.cpp
+++ b/llvm/lib/Target/ARM/MCTargetDesc/ARMMCCodeEmitter.cpp
@@ -272,7 +272,25 @@ public:
   unsigned getSOImmOpValue(const MCInst &MI, unsigned Op,
                            SmallVectorImpl<MCFixup> &Fixups,
                            const MCSubtargetInfo &STI) const {
-    unsigned SoImm = MI.getOperand(Op).getImm();
+
+    const MCOperand &MO = MI.getOperand(Op);
+
+    // We expect MO to be an immediate or an expression,
+    // if it is an immediate - that's fine, just encode the value.
+    // Otherwise - create a Fixup.
+    if (MO.isExpr()) {
+      const MCExpr *Expr = MO.getExpr();
+      // In instruction code this value always encoded as lowest 12 bits,
+      // so we don't have to perform any specific adjustments.
+      // Due to requirements of relocatable records we have to use FK_Data_4.
+      // See ARMELFObjectWriter::ExplicitRelSym and
+      //     ARMELFObjectWriter::GetRelocTypeInner for more details.
+      MCFixupKind Kind = MCFixupKind(FK_Data_4);
+      Fixups.push_back(MCFixup::Create(0, Expr, Kind, MI.getLoc()));
+      return 0;
+    }
+
+    unsigned SoImm = MO.getImm();
     int SoImmVal = ARM_AM::getSOImmVal(SoImm);
     assert(SoImmVal != -1 && "Not a valid so_imm value!");