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POStrange behavior using getchar() and -O3
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copied!<p>I have these two functions</p> <pre><code> void set_dram_channel_width(int channel_width){ printf("one\n"); getchar(); } void set_dram_transaction_granularity(int cacheline_size){ printf("two\n"); getchar(); } //output: one f //my keyboard input two one f //keyboard input two one f //keyboard input //No more calls </code></pre> <p>Then I change the functions to:</p> <pre><code> void set_dram_channel_width(int channel_width){ printf("one\n"); } void set_dram_transaction_granularity(int cacheline_size){ printf("two\n"); getchar(); } //output one two f //keyboard input //No more calls </code></pre> <p>Both functions are called by an external code, the code for both programs is the same, just changing the getchar() I get those two different outputs. Is this possible or there is something that is really wrong in my code?</p> <p>Thanks</p> <p>This is the output I get with GDB**</p> <p><em>For the first code</em></p> <pre><code>(gdb) break mem-dram.c:374 Breakpoint 1 at 0x71c810: file build/ALPHA_FS/mem/dramsim/mem-dram.c, line 374. (gdb) break mem-dram.c:381 Breakpoint 2 at 0x71c7b0: file build/ALPHA_FS/mem/dramsim/mem-dram.c, line 381. (gdb) run -d ./tmp/MyBench2/ one f [Switching to Thread 47368811512112 (LWP 17507)] Breakpoint 1, set_dram_channel_width (channel_width=64) (gdb) c Continuing. two one f Breakpoint 2, set_dram_transaction_granularity (cacheline_size=64) (gdb) c Continuing. Breakpoint 1, set_dram_channel_width (channel_width=8) 374 void set_dram_channel_width(int channel_width){ (gdb) c Continuing. two one f </code></pre> <p><em>For the second code</em></p> <pre><code>(gdb) break mem-dram.c:374 Breakpoint 1 at 0x71c7b6: file build/ALPHA_FS/mem/dramsim/mem-dram.c, line 374. (gdb) break mem-dram.c:380 Breakpoint 2 at 0x71c7f0: file build/ALPHA_FS/mem/dramsim/mem-dram.c, line 380. (gdb) run one two f [Switching to Thread 46985688772912 (LWP 17801)] Breakpoint 1, set_dram_channel_width (channel_width=64) (gdb) c Continuing. Breakpoint 2, set_dram_transaction_granularity (cacheline_size=64) (gdb) c Continuing. Breakpoint 1, set_dram_channel_width (channel_width=8) (gdb) c Continuing. </code></pre>

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