[SubZero] lower float and double constants for MIPS

tests_lit/llvm2ice_tests/fp_const_pool.ll

 ; This tests that different floating point constants (such as 0.0 and -0.0)
 ; remain distinct even when they sort of look equal, and also that different
 ; instances of the same floating point constant (such as NaN and NaN) get the
 ; same constant pool entry even when "a==a" would suggest they are different.
 
 ; REQUIRES: allow_dump
 
+; RUN: %if --need=target_MIPS32 --need=allow_dump \
+; RUN:   --command %p2i --filetype=asm --assemble --disassemble \
+; RUN:   --target mips32 -i %s --args -O2 --skip-unimplemented \
+; RUN:   | %if --need=target_MIPS32 --need=allow_dump \
+; RUN:   --command FileCheck --check-prefix MIPS32 %s
+
 define internal void @consume_float(float %f) {
   ret void
 }
 
 define internal void @consume_double(double %d) {
   ret void
 }
 
 define internal void @test_zeros() {
 entry:
   call void @consume_float(float 0.0)
   call void @consume_float(float -0.0)
   call void @consume_double(double 0.0)
   call void @consume_double(double -0.0)
   ret void
 }
+
+; MIPS32-LABEL: test_zeros
+; MIPS32: mtc1 zero,[[REG:.*]]
+; MIPS32: mov.s {{.*}},[[REG]]
+; MIPS32: lui [[REG:.*]],{{.*}}: R_MIPS_HI16 .L$float$80000000

[Jim Stichnoth, 2016/09/20 15:37:45]

This is OK for now, but I want to point out that these label names are not
guaranteed to be stable, i.e. in some future CL we may decide we need to change
the naming convention, and then any tests that rely on specific label names
would have to be changed as well.  Unlikely but possible.

The label names should always start with ".L" though.

It's probably better to match symbolically:
; MIPS32: ... R_MIPS_HI16 [[FLOAT_M0:\.L.*]]
and then use [[FLOAT_M0]] down in the constant pool definitions.

[jaydeep.patil, 2016/09/21 04:52:33]

Acknowledged.

+; MIPS32: lwc1 {{.*}},0([[REG]]) {{.*}}: R_MIPS_LO16 .L$float$80000000
+; MIPS32: mtc1 zero,[[REGLo:.*]]
+; MIPS32: mtc1 zero,[[REGHi:.*]]
+; MIPS32: mov.d {{.*}},[[REGLo]]
+; MIPS32: lui [[REG:.*]],{{.*}}: R_MIPS_HI16 .L$double$8000000000000000
+; MIPS32: ldc1 {{.*}},0([[REG]]) {{.*}}: R_MIPS_LO16 .L$double$8000000000000000
+
 ; Parse the function, dump the bitcode back out, and stop without translating.
 ; This tests that +0.0 and -0.0 aren't accidentally merged into a single
 ; zero-valued constant pool entry.
 ;
 ; RUN: %p2i -i %s --insts | FileCheck --check-prefix=ZERO %s
 ; ZERO: test_zeros
 ; ZERO-NEXT: entry:
 ; ZERO-NEXT: call void @consume_float(float 0.0
 ; ZERO-NEXT: call void @consume_float(float -0.0
 ; ZERO-NEXT: call void @consume_double(double 0.0
 ; ZERO-NEXT: call void @consume_double(double -0.0
 
 
 define internal void @test_nans() {
 entry:
   call void @consume_float(float 0x7FF8000000000000)
   call void @consume_float(float 0x7FF8000000000000)
   call void @consume_float(float 0xFFF8000000000000)
   call void @consume_float(float 0xFFF8000000000000)
   call void @consume_double(double 0x7FF8000000000000)
   call void @consume_double(double 0x7FF8000000000000)
   call void @consume_double(double 0xFFF8000000000000)
   call void @consume_double(double 0xFFF8000000000000)
   ret void
 }
+
+; MIPS32-LABEL: test_nans
+; MIPS32: lui [[REG:.*]],{{.*}}: R_MIPS_HI16 .L$float$7fc00000
+; MIPS32: lwc1 {{.*}},0([[REG]]) {{.*}}: R_MIPS_LO16 .L$float$7fc00000
+; MIPS32: lui [[REG:.*]],{{.*}}: R_MIPS_HI16 .L$float$7fc00000
+; MIPS32: lwc1 {{.*}},0([[REG]]) {{.*}}: R_MIPS_LO16 .L$float$7fc00000
+; MIPS32: lui [[REG:.*]],{{.*}}: R_MIPS_HI16 .L$float$ffc00000
+; MIPS32: lwc1 {{.*}},0([[REG]]) {{.*}}: R_MIPS_LO16 .L$float$ffc00000
+; MIPS32: lui [[REG:.*]],{{.*}}: R_MIPS_HI16 .L$float$ffc00000
+; MIPS32: lwc1 {{.*}},0([[REG]]) {{.*}}: R_MIPS_LO16 .L$float$ffc00000
+; MIPS32: lui [[REG:.*]],{{.*}}: R_MIPS_HI16 .L$double$7ff8000000000000
+; MIPS32: ldc1 {{.*}},0([[REG]]) {{.*}}: R_MIPS_LO16 .L$double$7ff8000000000000
+; MIPS32: lui [[REG:.*]],{{.*}}: R_MIPS_HI16 .L$double$7ff8000000000000
+; MIPS32: ldc1 {{.*}},0([[REG]]) {{.*}}: R_MIPS_LO16 .L$double$7ff8000000000000
+; MIPS32: lui [[REG:.*]],{{.*}}: R_MIPS_HI16 .L$double$fff8000000000000
+; MIPS32: ldc1 {{.*}},0([[REG]]) {{.*}}: R_MIPS_LO16 .L$double$fff8000000000000
+; MIPS32: lui [[REG:.*]],{{.*}}: R_MIPS_HI16 .L$double$fff8000000000000
+; MIPS32: ldc1 {{.*}},0([[REG]]) {{.*}}: R_MIPS_LO16 .L$double$fff8000000000000
+; MIPS32: jr ra
+
 ; The following tests check the emitted constant pool entries and make sure
 ; there is at most one entry for each NaN value.  We have to run a separate test
 ; for each NaN because the constant pool entries may be emitted in any order.
 ;
 ; RUN: %p2i -i %s --filetype=asm --llvm-source \
 ; RUN:   | FileCheck --check-prefix=NANS1 %s
 ; NANS1: float nan
 ; NANS1-NOT: float nan
 ;
 ; RUN: %p2i -i %s --filetype=asm --llvm-source \
 ; RUN:   | FileCheck --check-prefix=NANS2 %s
 ; NANS2: float -nan
 ; NANS2-NOT: float -nan
 ;
 ; RUN: %p2i -i %s --filetype=asm --llvm-source \
 ; RUN:   | FileCheck --check-prefix=NANS3 %s
 ; NANS3: double nan
 ; NANS3-NOT: double nan
 ;
 ; RUN: %p2i -i %s --filetype=asm --llvm-source \
 ; RUN:   | FileCheck --check-prefix=NANS4 %s
 ; NANS4: double -nan
 ; NANS4-NOT: double -nan
+
+; MIPS32 constant pool
+; RUN: %if --need=target_MIPS32 --command %p2i \
+; RUN:   --target mips32 -i %s --filetype=asm --llvm-source \
+; RUN:   --args -O2 --skip-unimplemented \
+; RUN:   | %if --need=target_MIPS32 --command FileCheck \
+; RUN:   --check-prefix=MIPS32CP %s
+; MIPS32CP-LABEL: .L$float$7fc00000:
+; MIPS32CP: .word 0x7fc00000 /* f32 nan */

[Jim Stichnoth, 2016/09/20 15:37:45]

Similar comment as above.  The "/* f32 nan */" part of the output is not
necessarily stable, so you could just match like this:
; MIPS32CP: .word 0x7fc00000

[jaydeep.patil, 2016/09/21 04:52:33]

Acknowledged.

+; MIPS32CP-LABEL: .L$float$80000000
+; MIPS32CP: .word 0x80000000 /* f32 -0.000000e+00 */
+; MIPS32CP-LABEL: .L$float$ffc00000
+; MIPS32CP: .word 0xffc00000 /* f32 -nan */
+; MIPS32CP-LABEL: .L$double$7ff8000000000000
+; MIPS32CP: .quad 0x7ff8000000000000 /* f64 nan */
+; MIPS32CP-LABEL: .L$double$8000000000000000
+; MIPS32CP: .quad 0x8000000000000000 /* f64 -0.000000e+00 */
+; MIPS32CP-LABEL: .L$double$fff8000000000000
+; MIPS32CP: .quad 0xfff8000000000000 /* f64 -nan */