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Carry facts about nullness and undef across GC relocation
This change implements four basic optimizations: If a relocated value isn't used, it doesn't need to be relocated. If the value being relocated is null, relocation doesn't change that. (Technically, this might be collector specific. I don't know of one which it doesn't work for though.) If the value being relocated is undef, the relocation is meaningless. If the value being relocated was known nonnull, the relocated pointer also isn't null. (Since it points to the same source language object.) I outlined other planned work in comments. Differential Revision: http://reviews.llvm.org/D6600 llvm-svn: 224968
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; RUN: opt < %s -instcombine -S | FileCheck %s | ||
; These tests check the optimizations specific to | ||
; pointers being relocated at a statepoint. | ||
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declare void @func() | ||
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define i1 @test_negative(i32 addrspace(1)* %p) { | ||
entry: | ||
%safepoint_token = tail call i32 (void ()*, i32, i32, ...)* @llvm.experimental.gc.statepoint.p0f_isVoidf(void ()* @func, i32 0, i32 0, i32 0, i32 addrspace(1)* %p) | ||
%pnew = call i32 addrspace(1)* @llvm.experimental.gc.relocate.p1i32(i32 %safepoint_token, i32 4, i32 4) | ||
%cmp = icmp eq i32 addrspace(1)* %pnew, null | ||
ret i1 %cmp | ||
; CHECK-LABEL: test_negative | ||
; CHECK: %pnew = call i32 addrspace(1)* | ||
; CHECK: ret i1 %cmp | ||
} | ||
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define i1 @test_nonnull(i32 addrspace(1)* nonnull %p) { | ||
entry: | ||
%safepoint_token = tail call i32 (void ()*, i32, i32, ...)* @llvm.experimental.gc.statepoint.p0f_isVoidf(void ()* @func, i32 0, i32 0, i32 0, i32 addrspace(1)* %p) | ||
%pnew = call i32 addrspace(1)* @llvm.experimental.gc.relocate.p1i32(i32 %safepoint_token, i32 4, i32 4) | ||
%cmp = icmp eq i32 addrspace(1)* %pnew, null | ||
ret i1 %cmp | ||
; CHECK-LABEL: test_nonnull | ||
; CHECK: ret i1 false | ||
} | ||
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define i1 @test_null() { | ||
entry: | ||
%safepoint_token = tail call i32 (void ()*, i32, i32, ...)* @llvm.experimental.gc.statepoint.p0f_isVoidf(void ()* @func, i32 0, i32 0, i32 0, i32 addrspace(1)* null) | ||
%pnew = call i32 addrspace(1)* @llvm.experimental.gc.relocate.p1i32(i32 %safepoint_token, i32 4, i32 4) | ||
%cmp = icmp eq i32 addrspace(1)* %pnew, null | ||
ret i1 %cmp | ||
; CHECK-LABEL: test_null | ||
; CHECK-NOT: %pnew | ||
; CHECK: ret i1 true | ||
} | ||
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define i1 @test_undef() { | ||
entry: | ||
%safepoint_token = tail call i32 (void ()*, i32, i32, ...)* @llvm.experimental.gc.statepoint.p0f_isVoidf(void ()* @func, i32 0, i32 0, i32 0, i32 addrspace(1)* undef) | ||
%pnew = call i32 addrspace(1)* @llvm.experimental.gc.relocate.p1i32(i32 %safepoint_token, i32 4, i32 4) | ||
%cmp = icmp eq i32 addrspace(1)* %pnew, null | ||
ret i1 %cmp | ||
; CHECK-LABEL: test_undef | ||
; CHECK-NOT: %pnew | ||
; CHECK: ret i1 undef | ||
} | ||
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declare i32 @llvm.experimental.gc.statepoint.p0f_isVoidf(void ()*, i32, i32, ...) | ||
declare i32 addrspace(1)* @llvm.experimental.gc.relocate.p1i32(i32, i32, i32) #3 |