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cmd/compile: Possible to synthesize base registers for PPC64 addressing? #17347

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dr2chase opened this issue Oct 5, 2016 · 2 comments
Closed

cmd/compile: Possible to synthesize base registers for PPC64 addressing? #17347

dr2chase opened this issue Oct 5, 2016 · 2 comments
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@dr2chase
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dr2chase commented Oct 5, 2016

Saw this while studying disassembly of math.test for #17109:

   111b0:       1e 00 e0 3f     lis     r31,30
   111b4:       b0 2d 9f e8     ld      r4,11696(r31)
   111b8:       1e 00 e0 3f     lis     r31,30
   111bc:       b8 2d bf e8     ld      r5,11704(r31)
   111c0:       1e 00 e0 3f     lis     r31,30
   111c4:       c0 2d df e8     ld      r6,11712(r31)
   111c8:       1e 00 e0 3f     lis     r31,30
   111cc:       70 2d ff e8     ld      r7,11632(r31)
   111d0:       1e 00 e0 3f     lis     r31,30
   111d4:       78 2d 1f e9     ld      r8,11640(r31)
   111d8:       1e 00 e0 3f     lis     r31,30
   111dc:       80 2d 3f e9     ld      r9,11648(r31)
   111e0:       1e 00 e0 3f     lis     r31,30
   111e4:       90 2d 5f e9     ld      r10,11664(r31)
   111e8:       1e 00 e0 3f     lis     r31,30
   111ec:       98 2d 7f e9     ld      r11,11672(r31)
   111f0:       1e 00 e0 3f     lis     r31,30
   111f4:       a0 2d 9f e9     ld      r12,11680(r31)

"lis" is load-immediate-shifted.

This comes from this ASM:

v44 00095 (/.../math/_test/_testmain.go:300) MOVD "".tests(SB), R4
v45 00096 (/.../math/_test/_testmain.go:300) MOVD "".tests+8(SB), R5
v47 00097 (/.../math/_test/_testmain.go:300) MOVD "".tests+16(SB), R6
v49 00098 (/.../math/_test/_testmain.go:300) MOVD "".benchmarks(SB), R7
v50 00099 (/.../math/_test/_testmain.go:300) MOVD "".benchmarks+8(SB), R8
v52 00100 (/.../math/_test/_testmain.go:300) MOVD "".benchmarks+16(SB), R9
v54 00101 (/.../math/_test/_testmain.go:300) MOVD "".examples(SB), R10
v55 00102 (/.../math/_test/_testmain.go:300) MOVD "".examples+8(SB), R11
v57 00103 (/.../math/_test/_testmain.go:300) MOVD "".examples+16(SB), R12

Doing better is an option -- we may not know the addressing relation between tests and benchmarks, but benchmarks and benchmarks+K is pretty obvious.
@laboger
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laboger commented Oct 5, 2016

This is a duplicate of #17110.

@dr2chase dr2chase closed this as completed Oct 5, 2016
@dr2chase
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dr2chase commented Oct 5, 2016

thanks for catching that

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