[binutils-gdb] gdb/testsuite/dap: fix gdb.dap/basic-dap.exp disassembly test for PIE

[Simon Marchi <simark@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=d4c4ea75838091b6bf52d97208bd2fa4021951db

commit d4c4ea75838091b6bf52d97208bd2fa4021951db
Author: Simon Marchi <simon.marchi@efficios.com>
Date:   Fri Jan 6 13:26:19 2023 -0500

    gdb/testsuite/dap: fix gdb.dap/basic-dap.exp disassembly test for PIE
    
    Prior to this patch, I get:
    
        >>> {"seq": 17, "type": "request", "command": "disassemble", "arguments": {"memoryReference": "0x115d", "instructionCount": 1}}
        Content-Length: 147
    
        {"request_seq": 17, "type": "response", "command": "disassemble", "success": false, "message": "Cannot access memory at address 0x115d", "seq": 41}FAIL: gdb.dap/basic-dap.exp: disassemble one instruction success
        FAIL: gdb.dap/basic-dap.exp: instructions in disassemble output
    
    The problem is that the PC to disassemble is taken from the breakpoint
    insertion response, which happens before running.  With a PIE
    executable, that PC is unrelocated, but the disassembly request happens
    after relocation.
    
    I chose to fix this by watching for a breakpoint changed event giving
    the new breakpoint address, and recording the address from there.  I
    think this is an interesting way to fix it, because it adds a bit of
    test coverage, I don't think these events are checked right now.
    
    Other ways to fix it would be:
    
     - Get the address by doing a breakpoint insertion after the program is
       started, or some other way.
     - Do the disassembly by symbol instead of by address.
     - Do the disassembly before running the program.
    
    Change-Id: I3c396f796ac4c8b22e7dfd2fa1c5467f7a47e84e

Diff:
---
 gdb/testsuite/gdb.dap/basic-dap.exp | 33 ++++++++++++++++++++++++++++++---
 1 file changed, 30 insertions(+), 3 deletions(-)

diff --git a/gdb/testsuite/gdb.dap/basic-dap.exp b/gdb/testsuite/gdb.dap/basic-dap.exp
index 795702a5a8f..5303e943320 100644
--- a/gdb/testsuite/gdb.dap/basic-dap.exp
+++ b/gdb/testsuite/gdb.dap/basic-dap.exp
@@ -90,9 +90,36 @@ set insn_pc [dict get [lindex $bplist 0] instructionReference]
 dap_check_request_and_response "start inferior" configurationDone
 dap_wait_for_event_and_check "inferior started" thread "body reason" started
 
-dap_wait_for_event_and_check "stopped at function breakpoint" stopped \
-    "body reason" breakpoint \
-    "body hitBreakpointIds" $fn_bpno
+# While waiting for the stopped event, we might receive breakpoint changed
+# events indicating some breakpoint addresses were relocated.  Update INSN_PC
+# if necessary.
+lassign [dap_wait_for_event_and_check "stopped at function breakpoint" stopped \
+	    "body reason" breakpoint \
+	    "body hitBreakpointIds" $fn_bpno] unused objs
+foreach obj $objs {
+    if { [dict get $obj "type"] != "event" } {
+	continue
+    }
+
+    if { [dict get $obj "event"] != "breakpoint" } {
+	continue
+    }
+
+    set body [dict get $obj "body"]
+
+    if { [dict get $body "reason"] != "changed" } {
+	continue
+    }
+
+    set breakpoint [dict get $body "breakpoint"]
+    set breakpoint_id [dict get $breakpoint "id"]
+
+    if { $breakpoint_id != $insn_bpno } {
+	continue
+    }
+
+    set insn_pc [dict get $breakpoint "instructionReference"]
+}
 
 set obj [dap_check_request_and_response "evaluate global in function" \
 	     evaluate {o expression [s global_variable]}]