ee5585ed09
Improve and enable folding of conditional branches with tail calls. 1. Make it so that conditional tail calls can be emitted even when there are multiple predecessors. 2. Don't guard the transformation behind -Os. The rationale for guarding it was static-prediction can be affected by whether the branch is forward of backward. This is no longer true for almost any X86 cpus (anything newer than `SnB`) so is no longer a meaningful concern. Reviewed By: pengfei Differential Revision: https://reviews.llvm.org/D140931
43 lines
987 B
LLVM
43 lines
987 B
LLVM
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
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; RUN: llc < %s -mtriple=x86_64-unknown-unknown | FileCheck %s
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declare dso_local void @bar()
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define void @test1(i64 %foo) nounwind {
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; CHECK-LABEL: test1:
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; CHECK: # %bb.0:
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; CHECK-NEXT: btq $32, %rdi
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; CHECK-NEXT: jb bar # TAILCALL
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; CHECK-NEXT: # %bb.1: # %if.end
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; CHECK-NEXT: retq
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%and = and i64 %foo, 4294967296
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%tobool = icmp eq i64 %and, 0
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br i1 %tobool, label %if.end, label %if.then
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if.then:
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tail call void @bar() nounwind
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br label %if.end
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if.end:
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ret void
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}
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define void @test2(i64 %foo) nounwind {
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; CHECK-LABEL: test2:
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; CHECK: # %bb.0:
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; CHECK-NEXT: testl %edi, %edi
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; CHECK-NEXT: js bar # TAILCALL
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; CHECK-NEXT: # %bb.1: # %if.end
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; CHECK-NEXT: retq
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%and = and i64 %foo, 2147483648
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%tobool = icmp eq i64 %and, 0
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br i1 %tobool, label %if.end, label %if.then
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if.then:
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tail call void @bar() nounwind
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br label %if.end
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if.end:
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ret void
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}
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