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9be926a88e
CGP tail-duplicates rets into blocks that end with a call that feed the ret. This puts the call in tail position, potentially allowing the DAG builder to lower it as a tail call. To avoid tail duplication in cases where we won't form the tail call, CGP tried to predict whether this is going to be possible, and avoids doing it when lowering as a tail call will definitely fail. However, it was being too conservative by always throwing away calls to functions with a signext/zeroext attribute on the return type. Instead, we can use the same logic the builder uses to determine whether the attributes work out. Differential Revision: https://reviews.llvm.org/D24315 llvm-svn: 280894
108 lines
2.8 KiB
LLVM
108 lines
2.8 KiB
LLVM
; RUN: llc < %s -mtriple=x86_64-apple-darwin | FileCheck %s
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; Teach CGP to dup returns to enable tail call optimization.
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; rdar://9147433
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define i32 @foo(i32 %x) nounwind ssp {
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; CHECK-LABEL: foo:
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entry:
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switch i32 %x, label %return [
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i32 1, label %sw.bb
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i32 2, label %sw.bb1
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i32 3, label %sw.bb3
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i32 4, label %sw.bb5
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i32 5, label %sw.bb7
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i32 6, label %sw.bb9
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]
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sw.bb: ; preds = %entry
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; CHECK: jmp _f1
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%call = tail call i32 @f1() nounwind
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br label %return
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sw.bb1: ; preds = %entry
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; CHECK: jmp _f2
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%call2 = tail call i32 @f2() nounwind
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br label %return
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sw.bb3: ; preds = %entry
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; CHECK: jmp _f3
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%call4 = tail call i32 @f3() nounwind
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br label %return
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sw.bb5: ; preds = %entry
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; CHECK: jmp _f4
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%call6 = tail call i32 @f4() nounwind
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br label %return
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sw.bb7: ; preds = %entry
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; CHECK: jmp _f5
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%call8 = tail call i32 @f5() nounwind
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br label %return
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sw.bb9: ; preds = %entry
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; CHECK: jmp _f6
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%call10 = tail call i32 @f6() nounwind
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br label %return
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return: ; preds = %entry, %sw.bb9, %sw.bb7, %sw.bb5, %sw.bb3, %sw.bb1, %sw.bb
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%retval.0 = phi i32 [ %call10, %sw.bb9 ], [ %call8, %sw.bb7 ], [ %call6, %sw.bb5 ], [ %call4, %sw.bb3 ], [ %call2, %sw.bb1 ], [ %call, %sw.bb ], [ 0, %entry ]
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ret i32 %retval.0
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}
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declare i32 @f1()
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declare i32 @f2()
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declare i32 @f3()
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declare i32 @f4()
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declare i32 @f5()
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declare i32 @f6()
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; rdar://11958338
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%0 = type opaque
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declare i8* @bar(i8*) uwtable optsize noinline ssp
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define hidden %0* @thingWithValue(i8* %self) uwtable ssp {
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entry:
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; CHECK-LABEL: thingWithValue:
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; CHECK: jmp _bar
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br i1 undef, label %if.then.i, label %if.else.i
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if.then.i: ; preds = %entry
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br label %someThingWithValue.exit
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if.else.i: ; preds = %entry
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%call4.i = tail call i8* @bar(i8* undef) optsize
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br label %someThingWithValue.exit
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someThingWithValue.exit: ; preds = %if.else.i, %if.then.i
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%retval.0.in.i = phi i8* [ undef, %if.then.i ], [ %call4.i, %if.else.i ]
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%retval.0.i = bitcast i8* %retval.0.in.i to %0*
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ret %0* %retval.0.i
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}
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; Correctly handle zext returns.
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declare zeroext i1 @foo_i1()
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; CHECK-LABEL: zext_i1
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; CHECK: jmp _foo_i1
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define zeroext i1 @zext_i1(i1 %k) {
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entry:
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br i1 %k, label %land.end, label %land.rhs
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land.rhs: ; preds = %entry
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%call1 = tail call zeroext i1 @foo_i1()
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br label %land.end
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land.end: ; preds = %entry, %land.rhs
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%0 = phi i1 [ false, %entry ], [ %call1, %land.rhs ]
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ret i1 %0
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}
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