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[AVR] Do not place functions in .progmem.data 

Previously, the AVR backend would put functions in .progmem.data. This
is probably a regression from when functions still lived in address
space 0. With this change, only global constants are placed in
.progmem.data.

This is not complete: avr-gcc additionally respects -fdata-sections for
progmem global constants, which LLVM doesn't yet do. But fixing that is
a bit more complicated (and I believe other backends such as RISC-V
might also have similar issues).

Differential Revision: https://reviews.llvm.org/D78212
This commit is contained in:
Ayke van Laethem 2020-04-15 17:30:47 +02:00
parent 9505b5cb66
commit 8aad119d93
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2 changed files with 32 additions and 1 deletions
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2
llvm/lib/Target/AVR/AVRTargetObjectFile.cpp
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@ -30,7 +30,7 @@ AVRTargetObjectFile::SelectSectionForGlobal(const GlobalObject *GO,
const TargetMachine &TM) const {
// Global values in flash memory are placed in the progmem.data section
// unless they already have a user assigned section.
if (AVR::isProgramMemoryAddress(GO) && !GO->hasSection())
if (AVR::isProgramMemoryAddress(GO) && !GO->hasSection() && Kind.isReadOnly())
return ProgmemDataSection;
// Otherwise, we work the same way as ELF.

31
llvm/test/CodeGen/AVR/sections.ll Normal file
View File

@ -0,0 +1,31 @@
; RUN: llc < %s -march=avr | FileCheck --check-prefixes=CHECK,NOSECTIONS %s
; RUN: llc -function-sections -data-sections < %s -march=avr | FileCheck --check-prefixes=CHECK,SECTIONS %s
; Test that functions (in address space 1) are not considered .progmem data.
; CHECK: .text
; SECTIONS: .text.somefunc,"ax",@progbits
; CHECK-LABEL: somefunc:
define void @somefunc() addrspace(1) {
ret void
}
; Test whether global variables are placed in the correct section.
; Note: avr-gcc would place this global in .progmem.data.flash with
; -fdata-sections. The AVR backend does not yet respect -fdata-sections in this
; case.
; CHECK: .section .progmem.data,"a",@progbits
; CHECK-LABEL: flash:
@flash = addrspace(1) constant i16 3
; NOSECTIONS: .section .rodata,"a",@progbits
; SECTIONS: .section .rodata.ram1,"a",@progbits
; CHECK-LABEL: ram1:
@ram1 = constant i16 3
; NOSECTIONS: .data
; SECTIONS: .section .data.ram2,"aw",@progbits
; CHECK-LABEL: ram2:
@ram2 = global i16 3