From b594c4c873bd3e2ee560cc83bd50282ec56b01e9 Mon Sep 17 00:00:00 2001 From: Richard Sandiford Date: Tue, 14 May 2013 09:47:26 +0000 Subject: [SystemZ] Rework handling of constant PC-relative operands The GNU assembler treats things like: brasl %r14, 100 in the same way as: brasl %r14, .+100 rather than as a branch to absolute address 100. We implemented this in LLVM by creating an immediate operand rather than the usual expr operand, and by handling immediate operands specially in the code emitter. This was undesirable for (at least) three reasons: - the specialness of immediate operands was exposed to the backend MC code, rather than being limited to the assembler parser. - in disassembly, an immediate operand really is an absolute address. (Note that this means reassembling printed disassembly can't recreate the original code.) - it would interfere with any assembly manipulation that we might try in future. E.g. operations like branch shortening can change the relative position of instructions, but any code that updates sym+offset addresses wouldn't update an immediate "100" operand in the same way as an explicit ".+100" operand. This patch changes the implementation so that the assembler creates a "." label for immediate PC-relative operands, so that the operand to the MCInst is always the absolute address. The patch also adds some error checking of the offset. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@181773 91177308-0d34-0410-b5e6-96231b3b80d8 --- test/MC/SystemZ/insn-brc-01.s | 13 +++++++++++++ 1 file changed, 13 insertions(+) (limited to 'test/MC/SystemZ/insn-brc-01.s') diff --git a/test/MC/SystemZ/insn-brc-01.s b/test/MC/SystemZ/insn-brc-01.s index a92ea45ecf..870f1c632e 100644 --- a/test/MC/SystemZ/insn-brc-01.s +++ b/test/MC/SystemZ/insn-brc-01.s @@ -1,5 +1,18 @@ # RUN: llvm-mc -triple s390x-linux-gnu -show-encoding %s | FileCheck %s +#CHECK: brc 0, .[[LAB:L.*]]-65536 # encoding: [0xa7,0x04,A,A] +#CHECK: fixup A - offset: 2, value: (.[[LAB]]-65536)+2, kind: FK_390_PC16DBL + brc 0, -0x10000 +#CHECK: brc 0, .[[LAB:L.*]]-2 # encoding: [0xa7,0x04,A,A] +#CHECK: fixup A - offset: 2, value: (.[[LAB]]-2)+2, kind: FK_390_PC16DBL + brc 0, -2 +#CHECK: brc 0, .[[LAB:L.*]] # encoding: [0xa7,0x04,A,A] +#CHECK: fixup A - offset: 2, value: .[[LAB]]+2, kind: FK_390_PC16DBL + brc 0, 0 +#CHECK: brc 0, .[[LAB:L.*]]+65534 # encoding: [0xa7,0x04,A,A] +#CHECK: fixup A - offset: 2, value: (.[[LAB]]+65534)+2, kind: FK_390_PC16DBL + brc 0, 0xfffe + #CHECK: brc 0, foo # encoding: [0xa7,0x04,A,A] #CHECK: fixup A - offset: 2, value: foo+2, kind: FK_390_PC16DBL brc 0, foo -- cgit v1.2.3