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llvm-project/llvm/test/CodeGen/AVR/PR37143.ll

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[AVR] Fix codegen bug in 16-bit loads Prior to this patch, the AVR::LDWRdPtr instruction was always lowered to instructions of this pattern: ld $GPR8, [PTR:XYZ]+ ld $GPR8, [PTR]+1 This has a problem; the [PTR] is incremented in-place once, but never decremented. Future uses of the same pointer will use the now clobbered value, leading to the pointer being incorrect by an offset of one. This patch modifies the expansion code of the LDWRdPtr pseudo instruction so that the pointer variable is not silently clobbered in future uses in the same live range. Bug first reported by Keshav Kini. Patch by Kaushik Phatak. llvm-svn: 351673
2019-01-20 11:41:08 +08:00
; RUN: llc -mattr=avr6,sram < %s -march=avr | FileCheck %s
[AVR] Disable register coalescing to the PTRDISPREGS class If we would allow register coalescing on PTRDISPREGS class then register allocator can lock Z register to some virtual register. Larger instructions requiring a memory acces then fail during the register allocation phase since there is no available register to hold a pointer if Y register was already taken for a stack frame. This patch prevents it by keeping Z register spillable. It does it by not allowing coalescer to lock it. Original discussion on https://github.com/avr-rust/rust/issues/128. llvm-svn: 362298
2019-06-01 20:38:56 +08:00
; CHECK: ld {{r[0-9]+}}, [[PTR:[XYZ]]]
[AVR] Fix codegen bug in 16-bit loads Prior to this patch, the AVR::LDWRdPtr instruction was always lowered to instructions of this pattern: ld $GPR8, [PTR:XYZ]+ ld $GPR8, [PTR]+1 This has a problem; the [PTR] is incremented in-place once, but never decremented. Future uses of the same pointer will use the now clobbered value, leading to the pointer being incorrect by an offset of one. This patch modifies the expansion code of the LDWRdPtr pseudo instruction so that the pointer variable is not silently clobbered in future uses in the same live range. Bug first reported by Keshav Kini. Patch by Kaushik Phatak. llvm-svn: 351673
2019-01-20 11:41:08 +08:00
; CHECK: ldd {{r[0-9]+}}, [[PTR]]+1
[AVR] Disable register coalescing to the PTRDISPREGS class If we would allow register coalescing on PTRDISPREGS class then register allocator can lock Z register to some virtual register. Larger instructions requiring a memory acces then fail during the register allocation phase since there is no available register to hold a pointer if Y register was already taken for a stack frame. This patch prevents it by keeping Z register spillable. It does it by not allowing coalescer to lock it. Original discussion on https://github.com/avr-rust/rust/issues/128. llvm-svn: 362298
2019-06-01 20:38:56 +08:00
; CHECK: st [[PTR2:[XYZ]]], {{r[0-9]+}}
; CHECK: std [[PTR2]]+1, {{r[0-9]+}}
[AVR] Fix codegen bug in 16-bit loads Prior to this patch, the AVR::LDWRdPtr instruction was always lowered to instructions of this pattern: ld $GPR8, [PTR:XYZ]+ ld $GPR8, [PTR]+1 This has a problem; the [PTR] is incremented in-place once, but never decremented. Future uses of the same pointer will use the now clobbered value, leading to the pointer being incorrect by an offset of one. This patch modifies the expansion code of the LDWRdPtr pseudo instruction so that the pointer variable is not silently clobbered in future uses in the same live range. Bug first reported by Keshav Kini. Patch by Kaushik Phatak. llvm-svn: 351673
2019-01-20 11:41:08 +08:00
define void @load_store_16(i16* nocapture %ptr) local_unnamed_addr #1 {
entry:
%0 = load i16, i16* %ptr, align 2
%add = add i16 %0, 5
store i16 %add, i16* %ptr, align 2
ret void
}