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55e622cae0
IndVarSimplify sometimes makes transforms basing on users that are trivially dead. In particular, if DCE wasn't run before it, there may be a dead `sext/zext` in loop that will trigger widening transforms, however it makes no sense to do it. This patch teaches IndVarsSimplify ignore the mist trivial cases of that. Differential Revision: https://reviews.llvm.org/D47974 Reviewed By: sanjoy llvm-svn: 334567
395 lines
11 KiB
LLVM
395 lines
11 KiB
LLVM
; RUN: opt -S -indvars %s | FileCheck %s
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target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
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target triple = "x86_64-unknown-linux-gnu"
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define void @test1(i64 %start) {
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; CHECK-LABEL: @test1
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entry:
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br label %loop
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loop:
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%indvars.iv = phi i64 [ %start, %entry ], [ %indvars.iv.next, %loop ]
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%indvars.iv.next = add nsw i64 %indvars.iv, 1
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; CHECK: %cmp1 = icmp slt i64 %start, -1
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%cmp1 = icmp slt i64 %indvars.iv, -1
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br i1 %cmp1, label %for.end, label %loop
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for.end: ; preds = %if.end, %entry
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ret void
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}
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define void @test2(i64 %start) {
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; CHECK-LABEL: @test2
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entry:
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br label %loop
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loop:
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%indvars.iv = phi i64 [ %start, %entry ], [ %indvars.iv.next, %loop ]
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%indvars.iv.next = add nsw i64 %indvars.iv, 1
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; CHECK: %cmp1 = icmp sle i64 %start, -1
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%cmp1 = icmp sle i64 %indvars.iv, -1
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br i1 %cmp1, label %for.end, label %loop
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for.end: ; preds = %if.end, %entry
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ret void
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}
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; As long as the test dominates the backedge, we're good
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define void @test3(i64 %start) {
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; CHECK-LABEL: @test3
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entry:
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br label %loop
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loop:
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%indvars.iv = phi i64 [ %start, %entry ], [ %indvars.iv.next, %backedge ]
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%indvars.iv.next = add nsw i64 %indvars.iv, 1
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%cmp = icmp eq i64 %indvars.iv.next, 25
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br i1 %cmp, label %backedge, label %for.end
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backedge:
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; prevent flattening, needed to make sure we're testing what we intend
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call void @foo()
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; CHECK: %cmp1 = icmp slt i64 %start, -1
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%cmp1 = icmp slt i64 %indvars.iv, -1
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br i1 %cmp1, label %for.end, label %loop
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for.end: ; preds = %if.end, %entry
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ret void
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}
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define void @test4(i64 %start) {
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; CHECK-LABEL: @test4
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entry:
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br label %loop
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loop:
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%indvars.iv = phi i64 [ %start, %entry ], [ %indvars.iv.next, %backedge ]
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%indvars.iv.next = add nsw i64 %indvars.iv, 1
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%cmp = icmp eq i64 %indvars.iv.next, 25
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br i1 %cmp, label %backedge, label %for.end
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backedge:
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; prevent flattening, needed to make sure we're testing what we intend
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call void @foo()
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; CHECK: %cmp1 = icmp sgt i64 %start, -1
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%cmp1 = icmp sgt i64 %indvars.iv, -1
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br i1 %cmp1, label %loop, label %for.end
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for.end: ; preds = %if.end, %entry
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ret void
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}
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define void @test5(i64 %start) {
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; CHECK-LABEL: @test5
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entry:
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br label %loop
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loop:
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%indvars.iv = phi i64 [ %start, %entry ], [ %indvars.iv.next, %backedge ]
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%indvars.iv.next = add nuw i64 %indvars.iv, 1
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%cmp = icmp eq i64 %indvars.iv.next, 25
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br i1 %cmp, label %backedge, label %for.end
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backedge:
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; prevent flattening, needed to make sure we're testing what we intend
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call void @foo()
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; CHECK: %cmp1 = icmp ugt i64 %start, 100
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%cmp1 = icmp ugt i64 %indvars.iv, 100
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br i1 %cmp1, label %loop, label %for.end
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for.end: ; preds = %if.end, %entry
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ret void
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}
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define void @test6(i64 %start) {
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; CHECK-LABEL: @test6
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entry:
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br label %loop
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loop:
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%indvars.iv = phi i64 [ %start, %entry ], [ %indvars.iv.next, %backedge ]
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%indvars.iv.next = add nuw i64 %indvars.iv, 1
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%cmp = icmp eq i64 %indvars.iv.next, 25
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br i1 %cmp, label %backedge, label %for.end
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backedge:
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; prevent flattening, needed to make sure we're testing what we intend
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call void @foo()
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; CHECK: %cmp1 = icmp ult i64 %start, 100
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%cmp1 = icmp ult i64 %indvars.iv, 100
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br i1 %cmp1, label %for.end, label %loop
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for.end: ; preds = %if.end, %entry
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ret void
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}
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define void @test7(i64 %start, i64* %inc_ptr) {
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; CHECK-LABEL: @test7
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entry:
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%inc = load i64, i64* %inc_ptr, !range !0
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%ok = icmp sge i64 %inc, 0
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br i1 %ok, label %loop, label %for.end
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loop:
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%indvars.iv = phi i64 [ %start, %entry ], [ %indvars.iv.next, %loop ]
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%indvars.iv.next = add nsw i64 %indvars.iv, %inc
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; CHECK: %cmp1 = icmp slt i64 %start, -1
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%cmp1 = icmp slt i64 %indvars.iv, -1
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br i1 %cmp1, label %for.end, label %loop
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for.end: ; preds = %if.end, %entry
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ret void
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}
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; Negative test - we can't show that the internal branch executes, so we can't
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; fold the test to a loop invariant one.
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define void @test1_neg(i64 %start) {
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; CHECK-LABEL: @test1_neg
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entry:
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br label %loop
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loop:
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%indvars.iv = phi i64 [ %start, %entry ], [ %indvars.iv.next, %backedge ]
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%indvars.iv.next = add nsw i64 %indvars.iv, 1
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%cmp = icmp eq i64 %indvars.iv.next, 25
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br i1 %cmp, label %backedge, label %skip
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skip:
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; prevent flattening, needed to make sure we're testing what we intend
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call void @foo()
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; CHECK: %cmp1 = icmp slt i64 %indvars.iv, -1
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%cmp1 = icmp slt i64 %indvars.iv, -1
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br i1 %cmp1, label %for.end, label %backedge
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backedge:
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; prevent flattening, needed to make sure we're testing what we intend
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call void @foo()
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br label %loop
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for.end: ; preds = %if.end, %entry
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ret void
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}
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; Slightly subtle version of @test4 where the icmp dominates the backedge,
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; but the exit branch doesn't.
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define void @test2_neg(i64 %start) {
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; CHECK-LABEL: @test2_neg
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entry:
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br label %loop
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loop:
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%indvars.iv = phi i64 [ %start, %entry ], [ %indvars.iv.next, %backedge ]
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%indvars.iv.next = add nsw i64 %indvars.iv, 1
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%cmp = icmp eq i64 %indvars.iv.next, 25
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; CHECK: %cmp1 = icmp slt i64 %indvars.iv, -1
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%cmp1 = icmp slt i64 %indvars.iv, -1
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br i1 %cmp, label %backedge, label %skip
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skip:
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; prevent flattening, needed to make sure we're testing what we intend
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call void @foo()
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br i1 %cmp1, label %for.end, label %backedge
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backedge:
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; prevent flattening, needed to make sure we're testing what we intend
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call void @foo()
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br label %loop
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for.end: ; preds = %if.end, %entry
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ret void
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}
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; The branch has to exit the loop if the condition is true
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define void @test3_neg(i64 %start) {
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; CHECK-LABEL: @test3_neg
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entry:
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br label %loop
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loop:
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%indvars.iv = phi i64 [ %start, %entry ], [ %indvars.iv.next, %loop ]
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%indvars.iv.next = add nsw i64 %indvars.iv, 1
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; CHECK: %cmp1 = icmp slt i64 %indvars.iv, -1
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%cmp1 = icmp slt i64 %indvars.iv, -1
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br i1 %cmp1, label %loop, label %for.end
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for.end: ; preds = %if.end, %entry
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ret void
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}
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define void @test4_neg(i64 %start) {
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; CHECK-LABEL: @test4_neg
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entry:
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br label %loop
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loop:
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%indvars.iv = phi i64 [ %start, %entry ], [ %indvars.iv.next, %backedge ]
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%indvars.iv.next = add nsw i64 %indvars.iv, 1
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%cmp = icmp eq i64 %indvars.iv.next, 25
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br i1 %cmp, label %backedge, label %for.end
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backedge:
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; prevent flattening, needed to make sure we're testing what we intend
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call void @foo()
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; CHECK: %cmp1 = icmp sgt i64 %indvars.iv, -1
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%cmp1 = icmp sgt i64 %indvars.iv, -1
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; %cmp1 can be made loop invariant only if the branch below goes to
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; %the header when %cmp1 is true.
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br i1 %cmp1, label %for.end, label %loop
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for.end: ; preds = %if.end, %entry
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ret void
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}
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define void @test5_neg(i64 %start, i64 %inc) {
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; CHECK-LABEL: @test5_neg
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entry:
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br label %loop
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loop:
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%indvars.iv = phi i64 [ %start, %entry ], [ %indvars.iv.next, %loop ]
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%indvars.iv.next = add nsw i64 %indvars.iv, %inc
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; CHECK: %cmp1 = icmp slt i64 %indvars.iv, -1
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%cmp1 = icmp slt i64 %indvars.iv, -1
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br i1 %cmp1, label %for.end, label %loop
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for.end: ; preds = %if.end, %entry
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ret void
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}
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define void @test8(i64 %start, i64* %inc_ptr) {
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; CHECK-LABEL: @test8
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entry:
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%inc = load i64, i64* %inc_ptr, !range !1
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%ok = icmp sge i64 %inc, 0
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br i1 %ok, label %loop, label %for.end
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loop:
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%indvars.iv = phi i64 [ %start, %entry ], [ %indvars.iv.next, %loop ]
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%indvars.iv.next = add nsw i64 %indvars.iv, %inc
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; CHECK: %cmp1 = icmp slt i64 %indvars.iv, -1
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%cmp1 = icmp slt i64 %indvars.iv, -1
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br i1 %cmp1, label %for.end, label %loop
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for.end: ; preds = %if.end, %entry
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ret void
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}
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; check to handle loops without preheaders, but invariant operands
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; (we handle this today by inserting a preheader)
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define void @test9(i1 %cnd, i64 %start) {
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; CHECK-LABEL: @test9
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; CHECK-LABEL: loop.preheader:
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entry:
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br i1 %cnd, label %entry1, label %entry2
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entry1:
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br label %loop
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entry2:
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br label %loop
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loop:
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%indvars.iv = phi i64 [ %start, %entry1 ],[ %start, %entry2 ], [ %indvars.iv.next, %loop ]
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%indvars.iv.next = add nsw i64 %indvars.iv, 1
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; CHECK: %cmp1 = icmp slt i64 %start, -1
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%cmp1 = icmp slt i64 %indvars.iv, -1
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br i1 %cmp1, label %for.end, label %loop
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for.end: ; preds = %if.end, %entry
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ret void
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}
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declare void @use(i1 %x)
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; check that we handle conditions with loop invariant operands which
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; *aren't* in the header - this is a very rare and fragile case where
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; we have a "loop" which is known to run exactly one iteration but
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; haven't yet simplified the uses of the IV
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define void @test10() {
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; CHECK-LABEL: @test10
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entry:
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br label %loop
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loop:
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%phi1 = phi i32 [ %phi2, %latch ], [ 0, %entry ]
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%dec = add i32 %phi1, -1
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br i1 false, label %left, label %right
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left:
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br label %latch
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right:
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br label %latch
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latch:
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%phi2 = phi i32 [ %phi1, %left ], [ %dec, %right ]
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; CHECK: %cmp = icmp slt i32 -1, undef
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%cmp = icmp slt i32 %phi2, undef
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br i1 true, label %exit, label %loop
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exit:
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call void @use(i1 %cmp)
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ret void
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}
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; check that we can figure out that iv.next > 1 from the facts that iv >= 0 and
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; iv.start != 0.
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define void @test11(i64* %inc_ptr) {
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; CHECK-LABEL: @test11
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entry:
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%inc = load i64, i64* %inc_ptr, !range !0
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%ne.cond = icmp ne i64 %inc, 0
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br i1 %ne.cond, label %loop, label %exit
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loop:
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%iv = phi i64 [ %inc, %entry ], [ %iv.next, %backedge ]
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%iv.next = add i64 %iv, 1
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%brcond = icmp sgt i64 %iv.next, 1
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; CHECK: br i1 true, label %if.true, label %if.false
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br i1 %brcond, label %if.true, label %if.false
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if.true:
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br label %backedge
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if.false:
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br label %backedge
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backedge:
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%loopcond = icmp slt i64 %iv, 200
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br i1 %loopcond, label %loop, label %exit
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exit:
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ret void
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}
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; check that we can prove that a recurrency is greater than another recurrency
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; in the same loop, with the same step, and with smaller starting value.
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define void @test12(i64* %inc_ptr) {
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; CHECK-LABEL: @test12
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entry:
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%inc = load i64, i64* %inc_ptr, !range !0
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%inc.minus.1 = sub i64 %inc, 1
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br label %loop
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loop:
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%iv = phi i64 [ %inc, %entry ], [ %iv.next, %backedge ]
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%iv.minus.1 = phi i64 [ %inc.minus.1, %entry ], [ %iv.minus.1.next, %backedge ]
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%iv.next = add i64 %iv, 1
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%iv.minus.1.next = add i64 %iv.minus.1, 1
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%brcond = icmp sgt i64 %iv.next, %iv.minus.1.next
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; CHECK: br i1 true, label %if.true, label %if.false
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br i1 %brcond, label %if.true, label %if.false
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if.true:
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br label %backedge
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if.false:
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br label %backedge
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backedge:
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%loopcond = icmp slt i64 %iv, 200
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br i1 %loopcond, label %loop, label %exit
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exit:
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ret void
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}
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!0 = !{i64 0, i64 100}
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!1 = !{i64 -1, i64 100}
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declare void @foo()
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