66182d6c38
The commit rL308422 introduces a restriction for folding unconditional branches. Specifically if empty block with unconditional branch leads to header of the loop then elimination of this basic block is prohibited. However it seems this condition is redundantly strict. If elimination of this basic block does not introduce more back edges then we can eliminate this block. The patch implements this relax of restriction. The test profile/Linux/counter_promo_nest.c in compiler-rt project is updated to meet this change. Reviewers: efriedma, mcrosier, pacxx, hsung, davidxl Reviewed By: pacxx Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D42691 llvm-svn: 324572
78 lines
2.9 KiB
LLVM
78 lines
2.9 KiB
LLVM
;RUN: opt -loop-unswitch -simplifycfg -S < %s | FileCheck %s
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define i32 @foo(i32 %a, i32 %b) {
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;CHECK-LABEL: foo
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entry:
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br label %for.body.lr.ph
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for.body.lr.ph: ; preds = %entry
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%cmp0 = icmp sgt i32 %b, 0
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br i1 %cmp0, label %for.body, label %for.cond.cleanup
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for.body: ; preds = %for.inc, %for.body.lr.ph
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%inc.i = phi i32 [ 0, %for.body.lr.ph ], [ %inc, %for.inc ]
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%mul.i = phi i32 [ 3, %for.body.lr.ph ], [ %mul.p, %for.inc ]
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%add.i = phi i32 [ %a, %for.body.lr.ph ], [ %add.p, %for.inc ]
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%cmp1 = icmp eq i32 %a, 12345
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br i1 %cmp1, label %if.then, label %if.else, !prof !0
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; CHECK: %cmp1 = icmp eq i32 %a, 12345
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; CHECK-NEXT: br i1 %cmp1, label %for.body.us, label %for.body, !prof !0
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if.then: ; preds = %for.body
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; CHECK: for.body.us:
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; CHECK: add nsw i32 %{{.*}}, 123
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; CHECK: %exitcond.us = icmp eq i32 %inc.us, %b
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; CHECK: br i1 %exitcond.us, label %for.cond.cleanup, label %for.body.us
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%add = add nsw i32 %add.i, 123
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br label %for.inc
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if.else: ; preds = %for.body
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%mul = mul nsw i32 %mul.i, %b
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br label %for.inc
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; CHECK: for.body:
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; CHECK: %mul = mul nsw i32 %mul.i, %b
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; CHECK: %inc = add nuw nsw i32 %inc.i, 1
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; CHECK: %exitcond = icmp eq i32 %inc, %b
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; CHECK: br i1 %exitcond, label %for.cond.cleanup, label %for.body
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for.inc: ; preds = %if.then, %if.else
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%mul.p = phi i32 [ %b, %if.then ], [ %mul, %if.else ]
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%add.p = phi i32 [ %add, %if.then ], [ %a, %if.else ]
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%inc = add nuw nsw i32 %inc.i, 1
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%exitcond = icmp eq i32 %inc, %b
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br i1 %exitcond, label %for.cond.cleanup, label %for.body
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for.cond.cleanup: ; preds = %for.inc, %for.body.lr.ph
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%t2 = phi i32 [ %b, %for.body.lr.ph ], [ %mul.p, %for.inc ]
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%t1 = phi i32 [ %a, %for.body.lr.ph ], [ %add.p, %for.inc ]
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%add3 = add nsw i32 %t2, %t1
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ret i32 %add3
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}
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define void @foo_swapped(i32 %a, i32 %b) {
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;CHECK-LABEL: foo_swapped
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entry:
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br label %for.body
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;CHECK: entry:
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;CHECK-NEXT: %cmp1 = icmp eq i32 1, 2
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;CHECK-NEXT: br i1 %cmp1, label %for.body, label %for.cond.cleanup.split, !prof !1
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;CHECK: for.body:
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for.body: ; preds = %for.inc, %entry
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%inc.i = phi i32 [ 0, %entry ], [ %inc, %if.then ]
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%add.i = phi i32 [ 100, %entry ], [ %add, %if.then ]
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%inc = add nuw nsw i32 %inc.i, 1
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%cmp1 = icmp eq i32 1, 2
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br i1 %cmp1, label %if.then, label %for.cond.cleanup, !prof !0
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if.then: ; preds = %for.body
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%add = add nsw i32 %a, %add.i
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%exitcond = icmp eq i32 %inc, %b
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br i1 %exitcond, label %for.cond.cleanup, label %for.body
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for.cond.cleanup: ; preds = %for.inc, %for.body.lr.ph, %for.body
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ret void
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}
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!0 = !{!"branch_weights", i32 64, i32 4}
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;CHECK: !0 = !{!"branch_weights", i32 64, i32 4}
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;CHECK: !1 = !{!"branch_weights", i32 4, i32 64}
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