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0fa193b086
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
222 lines
4.4 KiB
ArmAsm
222 lines
4.4 KiB
ArmAsm
@ This test has a partner (ldr-pseudo-darwin.s) that contains matching
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@ tests for the ldr-pseudo on darwin targets. We need separate files
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@ because the syntax for switching sections and temporary labels differs
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@ between darwin and linux. Any tests added here should have a matching
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@ test added there.
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@RUN: llvm-mc -triple armv7-unknown-linux-gnueabi %s | FileCheck %s
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@RUN: llvm-mc -triple thumbv5-unknown-linux-gnueabi %s | FileCheck %s
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@RUN: llvm-mc -triple thumbv7-unknown-linux-gnueabi %s | FileCheck %s
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@
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@ Check that large constants are converted to ldr from constant pool
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@
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@ simple test
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.section b,"ax",%progbits
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@ CHECK-LABEL: f3:
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f3:
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ldr r0, =0x10001
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@ CHECK: ldr r0, .Ltmp0
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@ loading multiple constants
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.section c,"ax",%progbits
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@ CHECK-LABEL: f4:
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f4:
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ldr r0, =0x10002
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@ CHECK: ldr r0, .Ltmp1
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adds r0, r0, #1
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adds r0, r0, #1
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adds r0, r0, #1
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adds r0, r0, #1
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ldr r0, =0x10003
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@ CHECK: ldr r0, .Ltmp2
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adds r0, r0, #1
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adds r0, r0, #1
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@ TODO: the same constants should have the same constant pool location
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.section d,"ax",%progbits
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@ CHECK-LABEL: f5:
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f5:
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ldr r0, =0x10004
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@ CHECK: ldr r0, .Ltmp3
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adds r0, r0, #1
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adds r0, r0, #1
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adds r0, r0, #1
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adds r0, r0, #1
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adds r0, r0, #1
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adds r0, r0, #1
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adds r0, r0, #1
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ldr r0, =0x10004
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@ CHECK: ldr r0, .Ltmp4
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adds r0, r0, #1
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adds r0, r0, #1
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adds r0, r0, #1
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adds r0, r0, #1
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adds r0, r0, #1
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adds r0, r0, #1
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@ a section defined in multiple pieces should be merged and use a single constant pool
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.section e,"ax",%progbits
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@ CHECK-LABEL: f6:
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f6:
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ldr r0, =0x10006
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@ CHECK: ldr r0, .Ltmp5
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adds r0, r0, #1
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adds r0, r0, #1
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adds r0, r0, #1
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.section f, "ax", %progbits
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@ CHECK-LABEL: f7:
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f7:
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adds r0, r0, #1
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adds r0, r0, #1
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adds r0, r0, #1
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.section e, "ax", %progbits
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@ CHECK-LABEL: f8:
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f8:
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adds r0, r0, #1
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ldr r0, =0x10007
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@ CHECK: ldr r0, .Ltmp6
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adds r0, r0, #1
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adds r0, r0, #1
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@
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@ Check that symbols can be loaded using ldr pseudo
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@
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@ load an undefined symbol
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.section g,"ax",%progbits
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@ CHECK-LABEL: f9:
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f9:
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ldr r0, =foo
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@ CHECK: ldr r0, .Ltmp7
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@ load a symbol from another section
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.section h,"ax",%progbits
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@ CHECK-LABEL: f10:
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f10:
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ldr r0, =f5
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@ CHECK: ldr r0, .Ltmp8
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@ load a symbol from the same section
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.section i,"ax",%progbits
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@ CHECK-LABEL: f11:
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f11:
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ldr r0, =f12
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@ CHECK: ldr r0, .Ltmp9
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@ CHECK-LABEL: f12:
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f12:
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adds r0, r0, #1
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adds r0, r0, #1
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.section j,"ax",%progbits
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@ mix of symbols and constants
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@ CHECK-LABEL: f13:
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f13:
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adds r0, r0, #1
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adds r0, r0, #1
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ldr r0, =0x101
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@ CHECK: ldr r0, .Ltmp10
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adds r0, r0, #1
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adds r0, r0, #1
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ldr r0, =bar
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@ CHECK: ldr r0, .Ltmp11
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adds r0, r0, #1
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adds r0, r0, #1
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@
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@ Check for correct usage in other contexts
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@
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@ usage in macro
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.macro useit_in_a_macro
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ldr r0, =0x10008
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ldr r0, =baz
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.endm
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.section k,"ax",%progbits
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@ CHECK-LABEL: f14:
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f14:
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useit_in_a_macro
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@ CHECK: ldr r0, .Ltmp12
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@ CHECK: ldr r0, .Ltmp13
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@ usage with expressions
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.section l, "ax", %progbits
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@ CHECK-LABEL: f15:
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f15:
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ldr r0, =0x10001+8
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@ CHECK: ldr r0, .Ltmp14
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adds r0, r0, #1
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ldr r0, =bar+4
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@ CHECK: ldr r0, .Ltmp15
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adds r0, r0, #1
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@
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@ Constant Pools
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@
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@ CHECK: .section b,"ax",%progbits
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@ CHECK: .align 2
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@ CHECK-LABEL: .Ltmp0:
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@ CHECK: .long 65537
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@ CHECK: .section c,"ax",%progbits
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@ CHECK: .align 2
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@ CHECK-LABEL: .Ltmp1:
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@ CHECK: .long 65538
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@ CHECK-LABEL: .Ltmp2:
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@ CHECK: .long 65539
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@ CHECK: .section d,"ax",%progbits
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@ CHECK: .align 2
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@ CHECK-LABEL: .Ltmp3:
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@ CHECK: .long 65540
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@ CHECK-LABEL: .Ltmp4:
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@ CHECK: .long 65540
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@ CHECK: .section e,"ax",%progbits
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@ CHECK: .align 2
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@ CHECK-LABEL: .Ltmp5:
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@ CHECK: .long 65542
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@ CHECK-LABEL: .Ltmp6:
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@ CHECK: .long 65543
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@ Should not switch to section because it has no constant pool
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@ CHECK-NOT: .section f,"ax",%progbits
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@ CHECK: .section g,"ax",%progbits
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@ CHECK: .align 2
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@ CHECK-LABEL: .Ltmp7:
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@ CHECK: .long foo
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@ CHECK: .section h,"ax",%progbits
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@ CHECK: .align 2
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@ CHECK-LABEL: .Ltmp8:
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@ CHECK: .long f5
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@ CHECK: .section i,"ax",%progbits
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@ CHECK: .align 2
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@ CHECK-LABEL: .Ltmp9:
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@ CHECK: .long f12
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@ CHECK: .section j,"ax",%progbits
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@ CHECK: .align 2
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@ CHECK-LABEL: .Ltmp10:
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@ CHECK: .long 257
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@ CHECK-LABEL: .Ltmp11:
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@ CHECK: .long bar
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@ CHECK: .section k,"ax",%progbits
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@ CHECK: .align 2
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@ CHECK-LABEL: .Ltmp12:
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@ CHECK: .long 65544
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@ CHECK-LABEL: .Ltmp13:
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@ CHECK: .long baz
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@ CHECK: .section l,"ax",%progbits
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@ CHECK: .align 2
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@ CHECK-LABEL: .Ltmp14:
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@ CHECK: .long 65545
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@ CHECK-LABEL: .Ltmp15:
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@ CHECK: .long bar+4
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