[sdcc-devel] [ sdcc-Bugs-3090354 ] C8051 - Code Size regression issue

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Bugs item #3090354, was opened at 2010-10-19 11:21
Message generated for change (Comment added) made by maartenbrock
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Category: mcs51(8051) target
>Group: fixed
>Status: Closed
>Resolution: Fixed
Priority: 5
Private: No
Submitted By: Robert Beyer (beartm)
>Assigned to: Maarten Brock (maartenbrock)
Summary: C8051 - Code Size regression issue

Initial Comment:
Regression Issue - Compiled code size has increased by 2 bytes for every unsigned comparison

For my application with 16K FLASH space, this change made an extra 148 bytes difference in code size.

I believe the issue is in /trunk/sdcc/src/mcs51/gen.c - Lines 6050+
  /* if unsigned char cmp with direct, do cjne A,right,zz */
  ...

The previous method without this added optimization was more efficient.
Example output from resulting assembly below:

---

C Code:
  bit bIRLevel;
  unsigned char nIRTime;

  if ((bIRLevel == HIGH) && ((nIRTime >= 70) && (nIRTime <= 75)))

---

Build 3.0.0 - (6028)

   0057                    1651 00208$:
                    0057   1652   C$main.c$354$3$3 ==.
                           1653 ; C:\Projects\SS01\SS01\main.c:354: if ((bIRLevel == HIGH) && ((nIRTime >= 70) && (nIRTime <= 75)))
   0057 20*33 03           1654   jb  _PCA0_ISR_bIRLevel_2_2,00209$
   005A 02s01r71           1655   ljmp  00149$
   005D                    1656 00209$:
   005D BC 46 00           1657   cjne  r4,#0x46,00210$
   0060                    1658 00210$:
   0060 50 03              1659   jnc 00211$
   0062 02s01r71           1660   ljmp  00149$
   0065                    1661 00211$:
   0065 74 4B              1662   mov a,#0x4B
   0067 B5 0C 00           1663   cjne  a,ar4,00212$
   006A                    1664 00212$:
   006A 50 03              1665   jnc 00213$
   006C 02s01r71           1666   ljmp  00149$
   006F                    1667 00213$:
                    006F   1668   C$main.c$357$4$4 ==.

---

Build 2.9.7 - (5862)

   0057                    1650 00208$:
                    0057   1651   C$main.c$354$3$3 ==.
                           1652 ; C:\Projects\SS01\SS01\main.c:354: if ((bIRLevel == HIGH) && ((nIRTime >= 70) && (nIRTime <= 75)))
   0057 20*33 03           1653   jb  _PCA0_ISR_bIRLevel_2_2,00209$
   005A 02s01r63           1654   ljmp  00149$
   005D                    1655 00209$:
   005D BC 46 00           1656   cjne  r4,#0x46,00210$
   0060                    1657 00210$:
   0060 50 03              1658   jnc 00211$
   0062 02s01r63           1659   ljmp  00149$
   0065                    1660 00211$:
   0065 EC                 1661   mov a,r4
   0066 24 B4              1662   add a,#0xff - 0x4B
   0068 50 03              1663   jnc 00212$
   006A 02s01r63           1664   ljmp  00149$
   006D                    1665 00212$:
                    006D   1666   C$main.c$357$4$4 ==.

---


----------------------------------------------------------------------

>Comment By: Maarten Brock (maartenbrock)
Date: 2011-02-20 21:41

Message:
Reverted and removed the 'optimization' in SDCC 3.0.1 #6241.

----------------------------------------------------------------------

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