23f657c165
Darwin platforms for both AArch64 and X86 can provide optimized `bzero()` routines. In this case, it may be preferable to use `bzero` in place of a memset of 0. This adds a G_BZERO generic opcode, similar to G_MEMSET et al. This opcode can be generated by platforms which may want to use bzero. To emit the G_BZERO, this adds a pre-legalize combine for AArch64. The conditions for this are largely a port of the bzero case in `AArch64SelectionDAGInfo::EmitTargetCodeForMemset`. The only difference in comparison to the SelectionDAG code is that, when compiling for minsize, this will fire for all memsets of 0. The original code notes that it's not beneficial to do this for small memsets; however, using bzero here will save a mov from wzr. For minsize, I think that it's preferable to prioritise omitting the mov. This also fixes a bug in the libcall legalization code which would delete instructions which could not be legalized. It also adds a check to make sure that we actually get a libcall name. Code size improvements (Darwin): - CTMark -Os: -0.0% geomean (-0.1% on pairlocalalign) - CTMark -Oz: -0.2% geomean (-0.5% on bullet) Differential Revision: https://reviews.llvm.org/D99358
34 lines
1.0 KiB
YAML
34 lines
1.0 KiB
YAML
#RUN: not --crash llc -o - -march=arm64 -run-pass=none -verify-machineinstrs %s 2>&1 | FileCheck %s
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# REQUIRES: aarch64-registered-target
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---
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name: test_bzero
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legalized: true
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regBankSelected: false
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selected: false
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tracksRegLiveness: true
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liveins:
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body: |
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bb.0:
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%ptr:_(p0) = G_IMPLICIT_DEF
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%cst1:_(s64) = G_CONSTANT i64 4
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%cst2:_(s8) = G_CONSTANT i8 7
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; CHECK: *** Bad machine code: bzero must have 1 memory operand ***
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G_BZERO %ptr, %cst2, 0
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; CHECK: *** Bad machine code: bzero memory operand must be a store ***
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G_BZERO %ptr, %cst2, 0 :: (load 4)
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; CHECK: *** Bad machine code: Missing mayLoad flag ***
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; CHECK: *** Bad machine code: bzero memory operand must be a store ***
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G_BZERO %ptr, %cst2, 0 :: (load store 4)
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; CHECK: *** Bad machine code: inconsistent bzero address space ***
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G_BZERO %ptr, %cst2, 0 :: (store 4, addrspace 1)
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; CHECK: *** Bad machine code: bzero operand must be a pointer ***
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G_BZERO %cst1, %cst2, 0 :: (store 4)
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...
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