MIPS: csum_partial.S CPU_DADDI_WORKAROUNDS bug fix

This change reverts most of commit
60724ca59eda766a30be57aec6b49bc3e2bead91 [MIPS: IP checksums: Remove
unncessary .set pseudos] that introduced warnings with the
CPU_DADDI_WORKAROUNDS option set:

arch/mips/lib/csum_partial.S: Assembler messages:
arch/mips/lib/csum_partial.S:467: Warning: used $3 with ".set at=$3"
arch/mips/lib/csum_partial.S:467: Warning: used $3 with ".set at=$3"
arch/mips/lib/csum_partial.S:467: Warning: used $3 with ".set at=$3"
arch/mips/lib/csum_partial.S:467: Warning: used $3 with ".set at=$3"
arch/mips/lib/csum_partial.S:467: Warning: used $3 with ".set at=$3"
arch/mips/lib/csum_partial.S:467: Warning: used $3 with ".set at=$3"
arch/mips/lib/csum_partial.S:467: Warning: used $3 with ".set at=$3"
arch/mips/lib/csum_partial.S:467: Warning: used $3 with ".set at=$3"
arch/mips/lib/csum_partial.S:467: Warning: used $3 with ".set at=$3"
arch/mips/lib/csum_partial.S:467: Warning: used $3 with ".set at=$3"
[...]
arch/mips/lib/csum_partial.S:577: Warning: used $3 with ".set at=$3"
arch/mips/lib/csum_partial.S:577: Warning: used $3 with ".set at=$3"
arch/mips/lib/csum_partial.S:577: Warning: used $3 with ".set at=$3"
arch/mips/lib/csum_partial.S:601: Warning: used $3 with ".set at=$3"
arch/mips/lib/csum_partial.S:601: Warning: used $3 with ".set at=$3"
arch/mips/lib/csum_partial.S:601: Warning: used $3 with ".set at=$3"
arch/mips/lib/csum_partial.S:601: Warning: used $3 with ".set at=$3"
[and so on, and so on...]

The warnings are benign and good code is produced regardless because no
macros that'd use the assembler's temporary register are involved, however
the `.set noat' directives removed by the commit referred are crucial to
guarantee this is still going to be the case after any changes in the
future.  Therefore they need to be brought back to place which this
change does.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/6686/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

diff --git a/arch/mips/lib/csum_partial.S b/arch/mips/lib/csum_partial.S
index 2e4825e..9901237 100644 (file)
--- a/arch/mips/lib/csum_partial.S
+++ b/arch/mips/lib/csum_partial.S
@@ -56,14 +56,20 @@
 #define UNIT(unit)  ((unit)*NBYTES)
 
 #define ADDC(sum,reg)                                          \
+       .set    push;                                           \
+       .set    noat;                                           \
        ADD     sum, reg;                                       \
        sltu    v1, sum, reg;                                   \
        ADD     sum, v1;                                        \
+       .set    pop
 
 #define ADDC32(sum,reg)                                                \
+       .set    push;                                           \
+       .set    noat;                                           \
        addu    sum, reg;                                       \
        sltu    v1, sum, reg;                                   \
        addu    sum, v1;                                        \
+       .set    pop
 
 #define CSUM_BIGCHUNK1(src, offset, sum, _t0, _t1, _t2, _t3)   \
        LOAD    _t0, (offset + UNIT(0))(src);                   \
@@ -710,6 +716,8 @@ LEAF(csum_partial)
        ADDC(sum, t2)
 .Ldone\@:
        /* fold checksum */
+       .set    push
+       .set    noat
 #ifdef USE_DOUBLE
        dsll32  v1, sum, 0
        daddu   sum, v1
@@ -732,6 +740,7 @@ LEAF(csum_partial)
        or      sum, sum, t0
 1:
 #endif
+       .set    pop
        .set reorder
        ADDC32(sum, psum)
        jr      ra