From ac9c99f7f6b86d536c60fcb4b5ecdd4a2e767603 Mon Sep 17 00:00:00 2001 From: Tom de Vries Date: Tue, 4 Feb 2025 14:06:20 +0100 Subject: [PATCH 45/46] [gdb/testsuite] Fix gdb.ada/convvar_comp.exp on s390x-linux When running test-case gdb.ada/convvar_comp.exp on s390x-linux, I get: ... (gdb) run ^M Starting program: pb16_063 ^M ^M Breakpoint 1, pck.break_me (item=...) at pck.adb:17^M 17 function Break_Me (Item : T) return Boolean is^M (gdb) print item.started^M Cannot access memory at address 0x0^M (gdb) FAIL: gdb.ada/convvar_comp.exp: print item.started ... This happens as follows. The parameter item is available in (DW_OP_fbreg: -168): ... <2><912>: Abbrev Number: 18 (DW_TAG_formal_parameter) <913> DW_AT_name : (indirect string, offset: 0x14ca): item <919> DW_AT_type : <0x929> <91d> DW_AT_location : 3 byte block: 91 d8 7e (DW_OP_fbreg: -168) ... and according to the rules of -O0, it's considered to be available after the prologue, which looks like this: ... 0000000001002998 : 1002998: b3 c1 00 2b ldgr %f2,%r11 100299c: b3 c1 00 0f ldgr %f0,%r15 10029a0: e3 f0 ff 58 ff 71 lay %r15,-168(%r15) 10029a6: b9 04 00 bf lgr %r11,%r15 10029aa: e3 20 b0 a0 00 24 stg %r2,160(%r11) ... To detect the prologue, gdb checks the line info, which looks like this: ... pck.adb: File name Line number Starting address View Stmt pck.adb 17 0x1002998 x pck.adb 17 0x1002998 1 x pck.adb 19 0x10029b0 x pck.adb 20 0x10029b8 x pck.adb - 0x10029c6 ... and gdb concludes that it's an empty prologue, so we stop at 0x1002998 and try to print parameter item, which is not available yet. For more details, see this comment in skip_prologue_using_sal: ... /* For languages other than assembly, treat two consecutive line entries at the same address as a zero-instruction prologue. ... The same thing happens on x86_64-linux, but it causes no problem there, because amd64_skip_prologue decides not to trust the result: ... struct compunit_symtab *cust = find_pc_compunit_symtab (func_addr); /* LLVM backend (Clang/Flang) always emits a line note before the prologue and another one after. We trust clang and newer Intel compilers to emit usable line notes. */ if (post_prologue_pc && (cust != NULL && cust->producer () != nullptr && (producer_is_llvm (cust->producer ()) || producer_is_icc_ge_19 (cust->producer ())))) return std::max (start_pc, post_prologue_pc); ... because the producer is GCC. Work around this by setting a breakpoint on the first statement of pck.break_me instead. Tested on s390x-linux. --- gdb/testsuite/gdb.ada/convvar_comp.exp | 4 +++- gdb/testsuite/gdb.ada/convvar_comp/pck.adb | 2 +- 2 files changed, 4 insertions(+), 2 deletions(-) diff --git a/gdb/testsuite/gdb.ada/convvar_comp.exp b/gdb/testsuite/gdb.ada/convvar_comp.exp index d59a19a40c3..e7ff3baa624 100644 --- a/gdb/testsuite/gdb.ada/convvar_comp.exp +++ b/gdb/testsuite/gdb.ada/convvar_comp.exp @@ -25,7 +25,9 @@ if {[gdb_compile_ada "${srcfile}" "${binfile}" executable [list debug ]] != "" } clean_restart ${testfile} -if {![runto "break_me"]} { +set bp_location [gdb_get_line_number "BREAK" "$testdir/pck.adb"] + +if {![runto pck.adb:$bp_location]} { return } diff --git a/gdb/testsuite/gdb.ada/convvar_comp/pck.adb b/gdb/testsuite/gdb.ada/convvar_comp/pck.adb index be5d8d719d8..b7bf3efe8f9 100644 --- a/gdb/testsuite/gdb.ada/convvar_comp/pck.adb +++ b/gdb/testsuite/gdb.ada/convvar_comp/pck.adb @@ -16,6 +16,6 @@ package body Pck is function Break_Me (Item : T) return Boolean is begin - return False; + return False; -- BREAK end Break_Me; end Pck; -- 2.43.0