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b344d5ac77
This gives a rough estimate of whether using pushes instead of movs is profitable, in terms of size. We go over all calls in the MachineFunction and compute: a) For each callsite that can not use pushes, the penalty of not having a reserved call frame. b) For each callsite that can use pushes, the gain of actually replacing the movs with pushes (and the potential penalty of having to readjust the stack). Differential Revision: http://reviews.llvm.org/D7561 llvm-svn: 228915
347 lines
9.5 KiB
LLVM
347 lines
9.5 KiB
LLVM
; RUN: llc < %s -mtriple=i686-windows | FileCheck %s -check-prefix=NORMAL
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; RUN: llc < %s -mtriple=x86_64-windows | FileCheck %s -check-prefix=X64
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; RUN: llc < %s -mtriple=i686-windows -force-align-stack -stack-alignment=32 | FileCheck %s -check-prefix=ALIGNED
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declare void @good(i32 %a, i32 %b, i32 %c, i32 %d)
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declare void @inreg(i32 %a, i32 inreg %b, i32 %c, i32 %d)
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declare void @oneparam(i32 %a)
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declare void @eightparams(i32 %a, i32 %b, i32 %c, i32 %d, i32 %e, i32 %f, i32 %g, i32 %h)
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; Here, we should have a reserved frame, so we don't expect pushes
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; NORMAL-LABEL: test1:
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; NORMAL: subl $16, %esp
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; NORMAL-NEXT: movl $4, 12(%esp)
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; NORMAL-NEXT: movl $3, 8(%esp)
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; NORMAL-NEXT: movl $2, 4(%esp)
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; NORMAL-NEXT: movl $1, (%esp)
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; NORMAL-NEXT: call
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; NORMAL-NEXT: addl $16, %esp
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define void @test1() {
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entry:
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call void @good(i32 1, i32 2, i32 3, i32 4)
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ret void
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}
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; We're optimizing for code size, so we should get pushes for x86,
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; even though there is a reserved call frame.
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; Make sure we don't touch x86-64
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; NORMAL-LABEL: test1b:
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; NORMAL-NOT: subl {{.*}} %esp
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; NORMAL: pushl $4
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; NORMAL-NEXT: pushl $3
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; NORMAL-NEXT: pushl $2
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; NORMAL-NEXT: pushl $1
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; NORMAL-NEXT: call
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; NORMAL-NEXT: addl $16, %esp
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; X64-LABEL: test1b:
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; X64: movl $1, %ecx
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; X64-NEXT: movl $2, %edx
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; X64-NEXT: movl $3, %r8d
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; X64-NEXT: movl $4, %r9d
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; X64-NEXT: callq good
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define void @test1b() optsize {
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entry:
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call void @good(i32 1, i32 2, i32 3, i32 4)
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ret void
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}
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; Same as above, but for minsize
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; NORMAL-LABEL: test1c:
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; NORMAL-NOT: subl {{.*}} %esp
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; NORMAL: pushl $4
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; NORMAL-NEXT: pushl $3
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; NORMAL-NEXT: pushl $2
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; NORMAL-NEXT: pushl $1
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; NORMAL-NEXT: call
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; NORMAL-NEXT: addl $16, %esp
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define void @test1c() minsize {
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entry:
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call void @good(i32 1, i32 2, i32 3, i32 4)
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ret void
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}
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; If we have a reserved frame, we should have pushes
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; NORMAL-LABEL: test2:
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; NORMAL-NOT: subl {{.*}} %esp
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; NORMAL: pushl $4
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; NORMAL-NEXT: pushl $3
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; NORMAL-NEXT: pushl $2
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; NORMAL-NEXT: pushl $1
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; NORMAL-NEXT: call
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define void @test2(i32 %k) {
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entry:
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%a = alloca i32, i32 %k
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call void @good(i32 1, i32 2, i32 3, i32 4)
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ret void
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}
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; Again, we expect a sequence of 4 immediate pushes
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; Checks that we generate the right pushes for >8bit immediates
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; NORMAL-LABEL: test2b:
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; NORMAL-NOT: subl {{.*}} %esp
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; NORMAL: pushl $4096
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; NORMAL-NEXT: pushl $3072
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; NORMAL-NEXT: pushl $2048
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; NORMAL-NEXT: pushl $1024
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; NORMAL-NEXT: call
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; NORMAL-NEXT: addl $16, %esp
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define void @test2b() optsize {
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entry:
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call void @good(i32 1024, i32 2048, i32 3072, i32 4096)
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ret void
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}
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; The first push should push a register
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; NORMAL-LABEL: test3:
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; NORMAL-NOT: subl {{.*}} %esp
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; NORMAL: pushl $4
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; NORMAL-NEXT: pushl $3
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; NORMAL-NEXT: pushl $2
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; NORMAL-NEXT: pushl %e{{..}}
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; NORMAL-NEXT: call
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; NORMAL-NEXT: addl $16, %esp
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define void @test3(i32 %k) optsize {
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entry:
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call void @good(i32 %k, i32 2, i32 3, i32 4)
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ret void
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}
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; We don't support weird calling conventions
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; NORMAL-LABEL: test4:
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; NORMAL: subl $12, %esp
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; NORMAL-NEXT: movl $4, 8(%esp)
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; NORMAL-NEXT: movl $3, 4(%esp)
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; NORMAL-NEXT: movl $1, (%esp)
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; NORMAL-NEXT: movl $2, %eax
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; NORMAL-NEXT: call
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; NORMAL-NEXT: addl $12, %esp
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define void @test4() optsize {
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entry:
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call void @inreg(i32 1, i32 2, i32 3, i32 4)
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ret void
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}
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; When there is no reserved call frame, check that additional alignment
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; is added when the pushes don't add up to the required alignment.
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; ALIGNED-LABEL: test5:
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; ALIGNED: subl $16, %esp
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; ALIGNED-NEXT: pushl $4
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; ALIGNED-NEXT: pushl $3
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; ALIGNED-NEXT: pushl $2
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; ALIGNED-NEXT: pushl $1
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; ALIGNED-NEXT: call
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define void @test5(i32 %k) {
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entry:
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%a = alloca i32, i32 %k
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call void @good(i32 1, i32 2, i32 3, i32 4)
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ret void
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}
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; When the alignment adds up, do the transformation
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; ALIGNED-LABEL: test5b:
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; ALIGNED: pushl $8
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; ALIGNED-NEXT: pushl $7
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; ALIGNED-NEXT: pushl $6
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; ALIGNED-NEXT: pushl $5
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; ALIGNED-NEXT: pushl $4
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; ALIGNED-NEXT: pushl $3
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; ALIGNED-NEXT: pushl $2
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; ALIGNED-NEXT: pushl $1
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; ALIGNED-NEXT: call
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define void @test5b() optsize {
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entry:
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call void @eightparams(i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7, i32 8)
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ret void
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}
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; When having to compensate for the alignment isn't worth it,
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; don't use pushes.
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; ALIGNED-LABEL: test5c:
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; ALIGNED: movl $1, (%esp)
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; ALIGNED-NEXT: call
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define void @test5c() optsize {
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entry:
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call void @oneparam(i32 1)
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ret void
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}
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; Check that pushing the addresses of globals (Or generally, things that
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; aren't exactly immediates) isn't broken.
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; Fixes PR21878.
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; NORMAL-LABEL: test6:
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; NORMAL: pushl $_ext
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; NORMAL-NEXT: call
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declare void @f(i8*)
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@ext = external constant i8
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define void @test6() {
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call void @f(i8* @ext)
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br label %bb
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bb:
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alloca i32
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ret void
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}
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; Check that we fold simple cases into the push
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; NORMAL-LABEL: test7:
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; NORMAL-NOT: subl {{.*}} %esp
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; NORMAL: movl 4(%esp), [[EAX:%e..]]
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; NORMAL-NEXT: pushl $4
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; NORMAL-NEXT: pushl ([[EAX]])
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; NORMAL-NEXT: pushl $2
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; NORMAL-NEXT: pushl $1
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; NORMAL-NEXT: call
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; NORMAL-NEXT: addl $16, %esp
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define void @test7(i32* %ptr) optsize {
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entry:
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%val = load i32* %ptr
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call void @good(i32 1, i32 2, i32 %val, i32 4)
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ret void
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}
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; But we don't want to fold stack-relative loads into the push,
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; because the offset will be wrong
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; NORMAL-LABEL: test8:
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; NORMAL-NOT: subl {{.*}} %esp
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; NORMAL: movl 4(%esp), [[EAX:%e..]]
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; NORMAL-NEXT: pushl $4
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; NORMAL-NEXT: pushl [[EAX]]
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; NORMAL-NEXT: pushl $2
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; NORMAL-NEXT: pushl $1
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; NORMAL-NEXT: call
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; NORMAL-NEXT: addl $16, %esp
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define void @test8(i32* %ptr) optsize {
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entry:
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%val = ptrtoint i32* %ptr to i32
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call void @good(i32 1, i32 2, i32 %val, i32 4)
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ret void
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}
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; If one function is using push instructions, and the other isn't
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; (because it has frame-index references), then we must resolve
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; these references correctly.
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; NORMAL-LABEL: test9:
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; NORMAL-NOT: leal (%esp),
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; NORMAL: pushl $4
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; NORMAL-NEXT: pushl $3
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; NORMAL-NEXT: pushl $2
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; NORMAL-NEXT: pushl $1
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; NORMAL-NEXT: call
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; NORMAL-NEXT: addl $16, %esp
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; NORMAL-NEXT: subl $16, %esp
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; NORMAL-NEXT: leal 16(%esp), [[EAX:%e..]]
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; NORMAL-NEXT: movl [[EAX]], 12(%esp)
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; NORMAL-NEXT: movl $7, 8(%esp)
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; NORMAL-NEXT: movl $6, 4(%esp)
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; NORMAL-NEXT: movl $5, (%esp)
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; NORMAL-NEXT: call
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; NORMAL-NEXT: addl $16, %esp
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define void @test9() optsize {
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entry:
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%p = alloca i32, align 4
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call void @good(i32 1, i32 2, i32 3, i32 4)
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%0 = ptrtoint i32* %p to i32
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call void @good(i32 5, i32 6, i32 7, i32 %0)
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ret void
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}
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; We can end up with an indirect call which gets reloaded on the spot.
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; Make sure we reference the correct stack slot - we spill into (%esp)
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; and reload from 16(%esp) due to the pushes.
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; NORMAL-LABEL: test10:
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; NORMAL: movl $_good, [[ALLOC:.*]]
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; NORMAL-NEXT: movl [[ALLOC]], [[EAX:%e..]]
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; NORMAL-NEXT: movl [[EAX]], (%esp) # 4-byte Spill
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; NORMAL: nop
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; NORMAL: pushl $4
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; NORMAL-NEXT: pushl $3
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; NORMAL-NEXT: pushl $2
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; NORMAL-NEXT: pushl $1
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; NORMAL-NEXT: calll *16(%esp)
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; NORMAL-NEXT: addl $16, %esp
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define void @test10() optsize {
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%stack_fptr = alloca void (i32, i32, i32, i32)*
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store void (i32, i32, i32, i32)* @good, void (i32, i32, i32, i32)** %stack_fptr
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%good_ptr = load volatile void (i32, i32, i32, i32)** %stack_fptr
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call void asm sideeffect "nop", "~{ax},~{bx},~{cx},~{dx},~{bp},~{si},~{di}"()
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call void (i32, i32, i32, i32)* %good_ptr(i32 1, i32 2, i32 3, i32 4)
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ret void
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}
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; We can't fold the load from the global into the push because of
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; interference from the store
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; NORMAL-LABEL: test11:
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; NORMAL: movl _the_global, [[EAX:%e..]]
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; NORMAL-NEXT: movl $42, _the_global
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; NORMAL-NEXT: pushl $4
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; NORMAL-NEXT: pushl $3
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; NORMAL-NEXT: pushl $2
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; NORMAL-NEXT: pushl [[EAX]]
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; NORMAL-NEXT: call
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; NORMAL-NEXT: addl $16, %esp
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@the_global = external global i32
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define void @test11() optsize {
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%myload = load i32* @the_global
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store i32 42, i32* @the_global
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call void @good(i32 %myload, i32 2, i32 3, i32 4)
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ret void
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}
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; Converting one mov into a push isn't worth it when
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; doing so forces too much overhead for other calls.
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; NORMAL-LABEL: test12:
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; NORMAL: subl $16, %esp
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; NORMAL-NEXT: movl $4, 8(%esp)
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; NORMAL-NEXT: movl $3, 4(%esp)
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; NORMAL-NEXT: movl $1, (%esp)
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; NORMAL-NEXT: movl $2, %eax
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; NORMAL-NEXT: calll _inreg
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; NORMAL-NEXT: movl $8, 12(%esp)
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; NORMAL-NEXT: movl $7, 8(%esp)
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; NORMAL-NEXT: movl $6, 4(%esp)
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; NORMAL-NEXT: movl $5, (%esp)
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; NORMAL-NEXT: calll _good
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; NORMAL-NEXT: movl $12, 8(%esp)
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; NORMAL-NEXT: movl $11, 4(%esp)
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; NORMAL-NEXT: movl $9, (%esp)
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; NORMAL-NEXT: movl $10, %eax
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; NORMAL-NEXT: calll _inreg
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; NORMAL-NEXT: addl $16, %esp
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define void @test12() optsize {
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entry:
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call void @inreg(i32 1, i32 2, i32 3, i32 4)
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call void @good(i32 5, i32 6, i32 7, i32 8)
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call void @inreg(i32 9, i32 10, i32 11, i32 12)
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ret void
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}
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; But if the gains outweigh the overhead, we should do it
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; NORMAL-LABEL: test12b:
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; NORMAL: pushl $4
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; NORMAL-NEXT: pushl $3
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; NORMAL-NEXT: pushl $2
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; NORMAL-NEXT: pushl $1
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; NORMAL-NEXT: calll _good
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; NORMAL-NEXT: addl $16, %esp
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; NORMAL-NEXT: subl $12, %esp
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; NORMAL-NEXT: movl $8, 8(%esp)
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; NORMAL-NEXT: movl $7, 4(%esp)
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; NORMAL-NEXT: movl $5, (%esp)
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; NORMAL-NEXT: movl $6, %eax
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; NORMAL-NEXT: calll _inreg
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; NORMAL-NEXT: addl $12, %esp
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; NORMAL-NEXT: pushl $12
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; NORMAL-NEXT: pushl $11
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; NORMAL-NEXT: pushl $10
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; NORMAL-NEXT: pushl $9
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; NORMAL-NEXT: calll _good
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; NORMAL-NEXT: addl $16, %esp
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define void @test12b() optsize {
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entry:
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call void @good(i32 1, i32 2, i32 3, i32 4)
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call void @inreg(i32 5, i32 6, i32 7, i32 8)
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call void @good(i32 9, i32 10, i32 11, i32 12)
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ret void
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}
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