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The ldr-pseudo opcode is a convenience for loading 32-bit constants. It is converted into a pc-relative load from a constant pool. For example, ldr r0, =0x10001 ldr r1, =bar will generate this output in the final assembly ldr r0, .Ltmp0 ldr r1, .Ltmp1 ... .Ltmp0: .long 0x10001 .Ltmp1: .long bar Sketch of the LDR pseudo implementation: Keep a map from Section => ConstantPool When parsing ldr r0, =val parse val as an MCExpr get ConstantPool for current Section Label = CreateTempSymbol() remember val in ConstantPool at next free slot add operand to ldr that is MCSymbolRef of Label On finishParse() callback Write out all non-empty constant pools for each Entry in ConstantPool Emit Entry.Label Emit Entry.Value Possible improvements to be added in a later patch: 1. Does not convert load of small constants to mov (e.g. ldr r0, =0x1 => mov r0, 0x1) 2. Does reuse constant pool entries for same constant The implementation was tested for ARM, Thumb1, and Thumb2 targets on linux and darwin. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@197708 91177308-0d34-0410-b5e6-96231b3b80d8
11 lines
268 B
ArmAsm
11 lines
268 B
ArmAsm
@RUN: not llvm-mc -triple=armv7-unknown-linux-gnueabi < %s 2>&1 | FileCheck %s
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@RUN: not llvm-mc -triple=armv7-apple-darwin < %s 2>&1 | FileCheck %s
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.text
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bar:
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mov r0, =0x101
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@ CHECK: error: unexpected token in operand
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@ CHECK: mov r0, =0x101
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@ CHECK: ^
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