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Teach perf annotate about the Alpha control-transfer instructions, so that
an Alpha perf.data gets call and jump arrows and resolved call targets,
whether it is read on Alpha or on another host.
Add tools/perf/util/annotate-arch/annotate-alpha.c with arch__new_alpha()
and an associate_instruction_ops() that classifies:
call: bsr, plus jsr and jcr as indirect calls
ret: ret
jump: br, the conditional branches beq/bne/blt/ble/bgt/bge/blbc/blbs
and fbeq/fbne/fblt/fble/fbgt/fbge, plus jmp as an indirect jump
mov: mov, fmov (objdump pseudos)
That is every mnemonic binutils can print for the branch and JSR formats.
jcr rather than jsr_coroutine, because both name the same MBR(0x1a,3)
encoding and print_insn_alpha() takes the first match in the table, where
the jcr alias has come first since the sources were imported in 1999.
bsr needs an Alpha-specific parse routine. The generic call__parse()
expects the operand string to begin with the target address, but a bsr
prints its return-address register first:
bsr t0,fffffc0001031dc0 <cserve_ena>
strtoull() then stops on the leading register name, leaving the target
address as 0, which makes call__scnprintf() fall back to printing the raw
operands and leaves target.sym unresolved so the browser cannot follow the
call. alpha_call__parse() takes the address from after the comma instead,
as s390_call__parse() does for the same reason. The PC-relative branches
need no such handling, as jump__parse() already skips up to two operands.
jsr and jmp get ins_ops that resolve no target at all. They transfer
control to a register, and their trailing operand is only a branch
prediction hint:
jsr ra,(t12),fffffc0001014ee8 <_printk>
binutils extracts that hint as a 14-bit signed field scaled by four and
prints it relative to the next instruction (extract_jhint() in alpha-opc.c,
print_insn_alpha() in alpha-dis.c), so it can name the callee only when the
callee lies within the resulting +-32KB. It also defaults to zero, which
prints as the next instruction. Of the 213750 jsr in a vmlinux built from
this tree, only 23093 hints land on a symbol; 157204 point into the middle
of an unrelated function and 33453 are that default. Parsing the hint
would therefore invent a call target for the majority of calls, so these
keep their operands, as an indirect call does elsewhere.
EM_ALPHA is 0x9026, far too large to index the e_machine-keyed
arch_new_fn[] table in arch__find(), so select arch__new_alpha explicitly
before the table lookup. Declare it in disasm.h and add the object to the
annotate-arch Build.
Disassembly itself comes from objdump/binutils, which already supports
Alpha; this provides perf's instruction-class metadata for annotation.
Tested on an EV7 Marvel, both natively and by annotating its perf.data on
an x86_64 host, over bsr to a local function, jsr through the PLT and
kernel-mode jsr; the two hosts produce identical output.
Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: Matt Turner <mattst88@gmail.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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