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https://github.com/c64scene-ar/llvm-6502.git
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02b5e72ac6
branch "br i1 %x, label %if_true, label %if_false" then it replaces "%x" with "true" in places only reachable via the %if_true arm, and with "false" in places only reachable via the %if_false arm. Except that actually it doesn't: if value numbering shows that %y is equal to %x then, yes, %y will be turned into true/false in this way, but any occurrences of %x itself are not transformed. Fix this. What's more, it's often the case that %x is an equality comparison such as "%x = icmp eq %A, 0", in which case every occurrence of %A that is only reachable via the %if_true arm can be replaced with 0. Implement this and a few other variations on this theme. This reduces the number of lines of LLVM IR in "GCC as one big file" by 0.2%. It has a bigger impact on Ada code, typically reducing the number of lines of bitcode by around 0.4% by removing repeated compiler generated checks. Passes the LLVM nightly testsuite and the Ada ACATS testsuite. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@141177 91177308-0d34-0410-b5e6-96231b3b80d8
100 lines
2.0 KiB
LLVM
100 lines
2.0 KiB
LLVM
; RUN: opt < %s -basicaa -gvn -S | FileCheck %s
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@a = external global i32 ; <i32*> [#uses=7]
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; CHECK: @test1
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define i32 @test1() nounwind {
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entry:
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%0 = load i32* @a, align 4
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%1 = icmp eq i32 %0, 4
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br i1 %1, label %bb, label %bb1
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bb: ; preds = %entry
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br label %bb8
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bb1: ; preds = %entry
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%2 = load i32* @a, align 4
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%3 = icmp eq i32 %2, 5
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br i1 %3, label %bb2, label %bb3
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bb2: ; preds = %bb1
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br label %bb8
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bb3: ; preds = %bb1
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%4 = load i32* @a, align 4
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%5 = icmp eq i32 %4, 4
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; CHECK: br i1 false, label %bb4, label %bb5
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br i1 %5, label %bb4, label %bb5
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bb4: ; preds = %bb3
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%6 = load i32* @a, align 4
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%7 = add i32 %6, 5
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br label %bb8
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bb5: ; preds = %bb3
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%8 = load i32* @a, align 4
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%9 = icmp eq i32 %8, 5
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; CHECK: br i1 false, label %bb6, label %bb7
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br i1 %9, label %bb6, label %bb7
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bb6: ; preds = %bb5
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%10 = load i32* @a, align 4
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%11 = add i32 %10, 4
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br label %bb8
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bb7: ; preds = %bb5
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%12 = load i32* @a, align 4
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br label %bb8
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bb8: ; preds = %bb7, %bb6, %bb4, %bb2, %bb
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%.0 = phi i32 [ %12, %bb7 ], [ %11, %bb6 ], [ %7, %bb4 ], [ 4, %bb2 ], [ 5, %bb ]
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br label %return
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return: ; preds = %bb8
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ret i32 %.0
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}
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declare void @foo(i1)
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; CHECK: @test2
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define void @test2(i1 %x, i1 %y) {
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%z = or i1 %x, %y
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br i1 %z, label %true, label %false
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true:
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; CHECK: true:
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%z2 = or i1 %x, %y
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call void @foo(i1 %z2)
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; CHECK: call void @foo(i1 true)
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br label %true
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false:
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; CHECK: false:
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%z3 = or i1 %x, %y
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call void @foo(i1 %z3)
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; CHECK: call void @foo(i1 false)
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br label %false
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}
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declare void @bar(i32)
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; CHECK: @test3
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define void @test3(i32 %x, i32 %y) {
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%xz = icmp eq i32 %x, 0
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%yz = icmp eq i32 %y, 0
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%z = and i1 %xz, %yz
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br i1 %z, label %both_zero, label %nope
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both_zero:
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call void @foo(i1 %xz)
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; CHECK: call void @foo(i1 true)
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call void @foo(i1 %yz)
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; CHECK: call void @foo(i1 true)
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call void @bar(i32 %x)
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; CHECK: call void @bar(i32 0)
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call void @bar(i32 %y)
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; CHECK: call void @bar(i32 0)
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ret void
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nope:
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call void @foo(i1 %z)
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; CHECK: call void @foo(i1 false)
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ret void
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}
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