Message ID | 4DB19D15.9020509@codesourcery.com |
---|---|
State | New |
Headers | show |
Ping. On 04/22/2011 11:21 PM, Chung-Lin Tang wrote: > Hi Richard, this part's for you. > > The ARM backend changes needed are very little after the prior patches, > basically just a case in arm_canonicalize_comparison() to detect > (zero_extend:SI (subreg:QI (reg:SI ...) 0)), and swap it into (and:SI > (reg:SI) #255). > > Had we not tried the combine modifications, this testcase probably could > have also be solved by implementing another version of the corresponding > *andsi3_compare0/_scratch patterns, with ZERO_EXTEND in the body, and > "ands" in the output assembly. Maybe that's an acceptable solution too... > > About the (ab)use of CANONICALIZE_COMPARISON, if it really should be > another macro/hook, then this ARM patch will need updating, but the code > should be similar. > > Thanks, > Chung-Lin
Ping. On 2011/5/9 11:02 PM, Chung-Lin Tang wrote: > Ping. > > On 04/22/2011 11:21 PM, Chung-Lin Tang wrote: >> Hi Richard, this part's for you. >> >> The ARM backend changes needed are very little after the prior patches, >> basically just a case in arm_canonicalize_comparison() to detect >> (zero_extend:SI (subreg:QI (reg:SI ...) 0)), and swap it into (and:SI >> (reg:SI) #255). >> >> Had we not tried the combine modifications, this testcase probably could >> have also be solved by implementing another version of the corresponding >> *andsi3_compare0/_scratch patterns, with ZERO_EXTEND in the body, and >> "ands" in the output assembly. Maybe that's an acceptable solution too... >> >> About the (ab)use of CANONICALIZE_COMPARISON, if it really should be >> another macro/hook, then this ARM patch will need updating, but the code >> should be similar. >> >> Thanks, >> Chung-Lin >
On 22/04/11 16:21, Chung-Lin Tang wrote: > Hi Richard, this part's for you. > > The ARM backend changes needed are very little after the prior patches, > basically just a case in arm_canonicalize_comparison() to detect > (zero_extend:SI (subreg:QI (reg:SI ...) 0)), and swap it into (and:SI > (reg:SI) #255). > > Had we not tried the combine modifications, this testcase probably could > have also be solved by implementing another version of the corresponding > *andsi3_compare0/_scratch patterns, with ZERO_EXTEND in the body, and > "ands" in the output assembly. Maybe that's an acceptable solution too... > > About the (ab)use of CANONICALIZE_COMPARISON, if it really should be > another macro/hook, then this ARM patch will need updating, but the code > should be similar. > > Thanks, > Chung-Lin > > > 3-arm-parts.diff > > > Index: config/arm/arm.c > =================================================================== > --- config/arm/arm.c (revision 172860) > +++ config/arm/arm.c (working copy) > @@ -3276,6 +3276,19 @@ > return code; > } > > + /* If *op0 is (zero_extend:SI (subreg:QI (reg:SI) 0)) and comparing > + with const0_rtx, change it to (and:SI (reg:SI) (const_int 255)), > + to facilitate possible combining with a cmp into 'ands'. */ > + if (mode == SImode > + && GET_CODE (*op0) == ZERO_EXTEND > + && GET_CODE (XEXP (*op0, 0)) == SUBREG > + && GET_MODE (XEXP (*op0, 0)) == QImode > + && GET_MODE (SUBREG_REG (XEXP (*op0, 0))) == SImode > + && SUBREG_BYTE (XEXP (*op0, 0)) == 0 > + && *op1 == const0_rtx) > + *op0 = gen_rtx_AND (SImode, SUBREG_REG (XEXP (*op0, 0)), > + GEN_INT (255)); > + This is wrong for big-endian code. You should use subreg_lowpart_p to check the subreg expression (after you've checked that you do have a subreg, of course). R.
Index: config/arm/arm.c =================================================================== --- config/arm/arm.c (revision 172860) +++ config/arm/arm.c (working copy) @@ -3276,6 +3276,19 @@ return code; } + /* If *op0 is (zero_extend:SI (subreg:QI (reg:SI) 0)) and comparing + with const0_rtx, change it to (and:SI (reg:SI) (const_int 255)), + to facilitate possible combining with a cmp into 'ands'. */ + if (mode == SImode + && GET_CODE (*op0) == ZERO_EXTEND + && GET_CODE (XEXP (*op0, 0)) == SUBREG + && GET_MODE (XEXP (*op0, 0)) == QImode + && GET_MODE (SUBREG_REG (XEXP (*op0, 0))) == SImode + && SUBREG_BYTE (XEXP (*op0, 0)) == 0 + && *op1 == const0_rtx) + *op0 = gen_rtx_AND (SImode, SUBREG_REG (XEXP (*op0, 0)), + GEN_INT (255)); + /* Comparisons smaller than DImode. Only adjust comparisons against an out-of-range constant. */ if (GET_CODE (*op1) != CONST_INT Index: testsuite/gcc.target/arm/combine-movs.c =================================================================== --- testsuite/gcc.target/arm/combine-movs.c (revision 0) +++ testsuite/gcc.target/arm/combine-movs.c (revision 0) @@ -0,0 +1,10 @@ +/* { dg-options "-O" } */ + +void foo (unsigned long r[], unsigned int d) +{ + int i, n = d / 32; + for (i = 0; i < n; ++i) + r[i] = 0; +} + +/* { dg-final { scan-assembler "movs\tr\[0-9\]" } } */ Index: testsuite/gcc.target/arm/unsigned-extend-2.c =================================================================== --- testsuite/gcc.target/arm/unsigned-extend-2.c (revision 0) +++ testsuite/gcc.target/arm/unsigned-extend-2.c (revision 0) @@ -0,0 +1,17 @@ +/* { dg-do compile } */ +/* { dg-options "-O -march=armv6" } */ + +unsigned short foo (unsigned short x) +{ + unsigned char i = 0; + for (i = 0; i < 8; i++) + { + x >>= 1; + x &= 0x7fff; + } + return x; +} + +/* { dg-final { scan-assembler "ands" } } */ +/* { dg-final { scan-assembler-not "uxtb" } } */ +/* { dg-final { scan-assembler-not "cmp" } } */