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f135e638ae
For large stack offsets the compiler generates multiple immediate mode sub/add instructions in the prologue/epilogue. This patch makes the compiler place the final amount to be added/subtracted into a register, which is then added/substracted with a single operation. Differential Revision: http://reviews.llvm.org/D7226 llvm-svn: 227458
60 lines
1.8 KiB
LLVM
60 lines
1.8 KiB
LLVM
; RUN: llc < %s -mtriple=x86_64-linux-unknown | FileCheck %s --check-prefix=CHECK-64
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; RUN: llc < %s -mtriple=i386-linux-unknown | FileCheck %s --check-prefix=CHECK-32
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; Test that a large stack offset uses a single add/sub instruction to
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; adjust the stack pointer.
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define void @foo() nounwind {
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; CHECK-64-LABEL: foo:
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; CHECK-64: movabsq $50000000{{..}}, %rax
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; CHECK-64-NEXT: subq %rax, %rsp
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; CHECK-64-NOT: subq $2147483647, %rsp
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; CHECK-64: movabsq $50000000{{..}}, [[RAX:%r..]]
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; CHECK-64-NEXT: addq [[RAX]], %rsp
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; CHECK-32-LABEL: foo:
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; CHECK-32: movl $50000000{{..}}, %eax
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; CHECK-32-NEXT: subl %eax, %esp
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; CHECK-32-NOT: subl $2147483647, %esp
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; CHECK-32: movl $50000000{{..}}, [[EAX:%e..]]
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; CHECK-32-NEXT: addl [[EAX]], %esp
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%1 = alloca [5000000000 x i8], align 16
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%2 = getelementptr inbounds [5000000000 x i8]* %1, i32 0, i32 0
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call void @bar(i8* %2)
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ret void
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}
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; Verify that we do not clobber the return value.
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define i32 @foo2() nounwind {
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; CHECK-64-LABEL: foo2:
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; CHECK-64: movl $10, %eax
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; CHECK-64-NOT: movabsq ${{.*}}, %rax
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; CHECK-32-LABEL: foo2:
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; CHECK-32: movl $10, %eax
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; CHECK-32-NOT: movl ${{.*}}, %eax
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%1 = alloca [5000000000 x i8], align 16
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%2 = getelementptr inbounds [5000000000 x i8]* %1, i32 0, i32 0
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call void @bar(i8* %2)
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ret i32 10
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}
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; Verify that we do not clobber EAX when using inreg attribute
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define i32 @foo3(i32 inreg %x) nounwind {
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; CHECK-64-LABEL: foo3:
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; CHECK-64: movabsq $50000000{{..}}, %rax
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; CHECK-64-NEXT: subq %rax, %rsp
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; CHECK-32-LABEL: foo3:
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; CHECK-32: subl $2147483647, %esp
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; CHECK-32-NOT: movl ${{.*}}, %eax
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%1 = alloca [5000000000 x i8], align 16
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%2 = getelementptr inbounds [5000000000 x i8]* %1, i32 0, i32 0
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call void @bar(i8* %2)
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ret i32 %x
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}
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declare void @bar(i8*)
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