From 7efbcc8c075c5e9ef69b2379b75b58a699f23eb3 Mon Sep 17 00:00:00 2001 From: Ravi Bangoria Date: Sat, 11 Sep 2021 10:08:53 +0530 Subject: perf annotate: Fix fused instr logic for assembly functions MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Some x86 microarchitectures fuse a subset of cmp/test/ALU instructions with branch instructions, and thus perf annotate highlight such valid pairs as fused. When annotated with source, perf uses struct disasm_line to contain either source or instruction line from objdump output. Usually, a C statement generates multiple instructions which include such cmp/test/ALU + branch instruction pairs. But in case of assembly function, each individual assembly source line generate one instruction. The 'perf annotate' instruction fusion logic assumes the previous disasm_line as the previous instruction line, which is wrong because, for assembly function, previous disasm_line contains source line. And thus perf fails to highlight valid fused instruction pairs for assembly functions. Fix it by searching backward until we find an instruction line and consider that disasm_line as fused with current branch instruction. Before: │ cmpq %rcx, RIP+8(%rsp) 0.00 │ cmp %rcx,0x88(%rsp) │ je .Lerror_bad_iret <--- Source line 0.14 │ ┌──je b4 <--- Instruction line │ │movl %ecx, %eax After: │ cmpq %rcx, RIP+8(%rsp) 0.00 │ ┌──cmp %rcx,0x88(%rsp) │ │je .Lerror_bad_iret 0.14 │ ├──je b4 │ │movl %ecx, %eax Reviewed-by: Jin Yao Signed-off-by: Ravi Bangoria Cc: Alexander Shishkin Cc: Jiri Olsa Cc: Kim Phillips Cc: Mark Rutland Cc: Namhyung Kim Link: https //lore.kernel.org/r/20210911043854.8373-1-ravi.bangoria@amd.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/ui/browser.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'tools/perf/ui/browser.h') diff --git a/tools/perf/ui/browser.h b/tools/perf/ui/browser.h index 3678eb88f119..510ce4554050 100644 --- a/tools/perf/ui/browser.h +++ b/tools/perf/ui/browser.h @@ -51,7 +51,7 @@ void ui_browser__write_graph(struct ui_browser *browser, int graph); void __ui_browser__line_arrow(struct ui_browser *browser, unsigned int column, u64 start, u64 end); void ui_browser__mark_fused(struct ui_browser *browser, unsigned int column, - unsigned int row, bool arrow_down); + unsigned int row, int diff, bool arrow_down); void __ui_browser__show_title(struct ui_browser *browser, const char *title); void ui_browser__show_title(struct ui_browser *browser, const char *title); int ui_browser__show(struct ui_browser *browser, const char *title, -- cgit