This issue was surfaced in b/122450679 and that issue is being closed by working around what appears to cause the breakpoint installation/handling error that this bug report is about.

When compiling with D8 1.3.54 (AGP 3.3) the result of compiling:

public class BreakOnIfTest {
public static void main(String[] args) {
if (args == null) {
System.out.println("args null");
}
System.out.println("after if");
}
}

is:

registers: 3, inputs: 1, outputs: 2
------------------------------------------------------------
inst# offset instruction arguments
------------------------------------------------------------
0x00, line 9, locals: [2 -> args]
0: 0x00: IfNez v2, 0x0a (+10)
0x02, line 10, locals: [2 -> args]
1: 0x02: SgetObject v0, Field java.io.PrintStream java.lang.System.out
2: 0x04: ConstString v1, "args null"
3: 0x06: InvokeVirtual { v0 v1 } Ljava/io/PrintStream;->println(Ljava/lang/String;)V
4: 0x09: Goto 0x0b (+2)
0x0a, line 9, locals: [2 -> args]
5: 0x0a: Nop
0x0b, line 12, locals: [2 -> args]
6: 0x0b: SgetObject v0, Field java.io.PrintStream java.lang.System.out
7: 0x0d: ConstString v1, "after if"
8: 0x0f: InvokeVirtual { v0 v1 } Ljava/io/PrintStream;->println(Ljava/lang/String;)V
0x12, line 13, locals: [2 -> args]
9: 0x12: ReturnVoid

Here the PCs for line 9 are {0x00, 0x0a}. When installing a breakpoint on line 9, it appears that Studio/Intellij will fail to install a breakpoint on PC 0x00. In the D8 debugger test infrastructure, setting a breakpoint on line 9 will result in a breakpoint installed on 0x00 and 0x0a and execution will hit and break twice. As a side note to this, it would be nice to ensure that the D8 testing infrastructure mirrors the studio behavior.

On tip-of-tree and after the fix for b/122450679 has landed, the output of D8 is:

registers: 3, inputs: 1, outputs: 2
------------------------------------------------------------
inst# offset instruction arguments
------------------------------------------------------------
0x00, line 9, locals: [2 -> args]
0: 0x00: IfNez v2, 0x09 (+9)
0x02, line 10, locals: [2 -> args]
1: 0x02: SgetObject v0, Field java.io.PrintStream java.lang.System.out
2: 0x04: ConstString v1, "args null"
3: 0x06: InvokeVirtual { v0 v1 } Ljava/io/PrintStream;->println(Ljava/lang/String;)V
0x09, line 12, locals: [2 -> args]
4: 0x09: SgetObject v0, Field java.io.PrintStream java.lang.System.out
5: 0x0b: ConstString v1, "after if"
6: 0x0d: InvokeVirtual { v0 v1 } Ljava/io/PrintStream;->println(Ljava/lang/String;)V
0x10, line 13, locals: [2 -> args]
7: 0x10: ReturnVoid

Here, the only PC for line 9 is 0x00 and studio/intellij does install and hit that breakpoint. The underlying issue however remains as D8 can't in general ensure that there is never a conditional after the branch at the same line. It is not clear if the issue in studio/intellij only occurs for a nop continuation at this point.

Issue 123863053

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