[Bug c/43104] New: Incorrect code generation for target mcu ATMega164P

[smal dot root at gmail dot com]

Source

volatile uint8_t mUsart0BufferReadPtr;

void Usart0AtModeSkipLine(void)
{
uint8_t rdptr = 0;

        rdptr = mUsart0BufferReadPtr;
        rdptr = mUsart0BufferReadPtr;
        rdptr = mUsart0BufferReadPtr;
}
-------------
Generated asm
+00000694:   93DF        PUSH      R29            Push register on stack
+00000695:   93CF        PUSH      R28            Push register on stack
+00000696:   920F        PUSH      R0             Push register on stack
+00000697:   B7CD        IN        R28,0x3D       In from I/O location
+00000698:   B7DE        IN        R29,0x3E       In from I/O location
179:      uint8_t rdptr = 0;
+00000699:   8219        STD       Y+1,R1         Store indirect with
displacement
181:            rdptr = mUsart0BufferReadPtr;
+0000069A:   91800000    LDS       R24,0x0000     Load direct from data space
+0000069C:   8389        STD       Y+1,R24        Store indirect with
displacement
182:            rdptr = mUsart0BufferReadPtr;
+0000069D:   91800264    LDS       R24,0x0264     Load direct from data space
+0000069F:   8389        STD       Y+1,R24        Store indirect with
displacement
183:            rdptr = mUsart0BufferReadPtr;
+000006A0:   91800264    LDS       R24,0x0264     Load direct from data space
+000006A2:   8389        STD       Y+1,R24        Store indirect with
displacement

------------------------
OS: WinXP
gcc: avr-gcc.EXE (WinAVR 20100110) 4.3.3


-- 
           Summary: Incorrect code generation for target mcu ATMega164P
           Product: gcc
           Version: 4.4.3
            Status: UNCONFIRMED
          Severity: major
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: smal dot root at gmail dot com
  GCC host triplet: Win32
GCC target triplet: avr


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43104