What I do to look at assembler is use "objdump" on the elf file. Just connect to the temporary directory that arduino uses for builds (/tmp/build* on my mac) and do something like:
MacOSX<1105> cd /tmp/build25808.tmp/
MacOSX<1106> /Downloads/arduino-0008/tools/avr/bin/avr-objdump -S hptime.elf
In theory, there's a -S switch for the compiler as well, but I worry about getting all the right switches and preprocessing done (automatically provided by audino environment), and using the .elf avoids this, and objdump produces a pretty nice mixed source/assembly listing:
Serial.print("millis = ");
12a: 60 e0 ldi r22, 0x00 ; 0
12c: 71 e0 ldi r23, 0x01 ; 1
12e: 86 e2 ldi r24, 0x26 ; 38
130: 91 e0 ldi r25, 0x01 ; 1
132: 0e 94 ec 00 call 0x1d8 <_ZN14HardwareSerial5printEPKc>
Serial.print(mstime);
136: b8 01 movw r22, r16
138: a7 01 movw r20, r14
13a: 86 e2 ldi r24, 0x26 ; 38
13c: 91 e0 ldi r25, 0x01 ; 1
13e: 0e 94 2a 01 call 0x254 <_ZN14HardwareSerial5printEm>
Serial.print(", high precision time = ");
142: 6a e0 ldi r22, 0x0A ; 10
144: 71 e0 ldi r23, 0x01 ; 1
146: 86 e2 ldi r24, 0x26 ; 38
148: 91 e0 ldi r25, 0x01 ; 1
14a: 0e 94 ec 00 call 0x1d8 <_ZN14HardwareSerial5printEPKc>
Serial.print(hptime);
14e: dc 2c mov r13, r12
150: cb 2c mov r12, r11
152: ba 2c mov r11, r10
154: aa 24 eor r10, r10