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029ad727ae
The x86 ret instruction has a 16 bit immediate indicating how many bytes to pop off of the stack beyond the return address. There is a problem when extremely large structs are passed by value: we might not be able to fit the number of bytes to pop into the return instruction. To fix this, expand RET_FLAG a little later and use a special sequence to clean the stack: pop %ecx ; return address is now in %ecx add $n, %esp ; clean the stack push %ecx ; bring the return address back on the stack ret ; pop the return address and jmp to it's value git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@262755 91177308-0d34-0410-b5e6-96231b3b80d8
23 lines
598 B
LLVM
23 lines
598 B
LLVM
; RUN: llc < %s | FileCheck %s
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target datalayout = "e-m:x-p:32:32-i64:64-f80:32-n8:16:32-a:0:32-S32"
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target triple = "i386-pc-windows-msvc"
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define x86_fastcallcc i32 @test1(i32 inreg %V, [65533 x i8]* byval %p_arg) {
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ret i32 %V
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}
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; CHECK-LABEL: @test1@65540:
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; CHECK: movl %ecx, %eax
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; CHECK-NEXT: popl %ecx
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; CHECK-NEXT: addl $65536, %esp
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; CHECK-NEXT: pushl %ecx
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; CHECK-NEXT: retl
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define x86_stdcallcc void @test2([65533 x i8]* byval %p_arg) {
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ret void
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}
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; CHECK-LABEL: _test2@65536:
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; CHECK: popl %ecx
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; CHECK-NEXT: addl $65536, %esp
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; CHECK-NEXT: pushl %ecx
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; CHECK-NEXT: retl
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