forked from OSchip/llvm-project
208 lines
7.7 KiB
LLVM
208 lines
7.7 KiB
LLVM
; RUN: opt < %s -S -loop-unroll -unroll-max-iteration-count-to-analyze=100 -unroll-dynamic-cost-savings-discount=1000 -unroll-threshold=10 -unroll-percent-dynamic-cost-saved-threshold=50 | FileCheck %s
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target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
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@known_constant = internal unnamed_addr constant [10 x i32] [i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1], align 16
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; We should be able to propagate constant data through comparisons.
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; For example, in this test we have a load, which becomes constant after
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; unrolling, making comparison with 0 also known to be 0 (false) - and that
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; will trigger further simplifications.
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;
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; We expect this loop to be unrolled, because in this case load would become
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; constant, which is always 1, and which, in its turn, helps to simplify
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; following comparison, zero-extension, and addition. In total, unrolling should help to
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; optimize more than 50% of all instructions in this case.
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;
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; CHECK-LABEL: @const_compare
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; CHECK-NOT: br i1 %
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; CHECK: ret i32
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define i32 @const_compare(i32* noalias nocapture readonly %b) {
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entry:
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br label %for.body
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for.body: ; preds = %for.inc, %entry
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%iv.0 = phi i64 [ 0, %entry ], [ %iv.1, %for.body ]
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%r.0 = phi i32 [ 0, %entry ], [ %r.1, %for.body ]
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%arrayidx1 = getelementptr inbounds [10 x i32], [10 x i32]* @known_constant, i64 0, i64 %iv.0
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%x1 = load i32, i32* %arrayidx1, align 4
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%cmp = icmp eq i32 %x1, 0
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%cast = zext i1 %cmp to i32
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%iv.1 = add nuw nsw i64 %iv.0, 1
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%r.1 = add i32 %r.0, %cast
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%exitcond = icmp eq i64 %iv.1, 10
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br i1 %exitcond, label %for.end, label %for.body
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for.end: ; preds = %for.inc
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ret i32 %r.1
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}
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; If we can figure out result of comparison on each iteration, we can resolve
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; the depending branch. That means, that the unrolled version of the loop would
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; have less code, because we don't need not-taken basic blocks there.
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; This test checks that this is taken into consideration.
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; We expect this loop to be unrolled, because the most complicated part of its
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; body (if.then block) is never actually executed.
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; CHECK-LABEL: @branch_folded
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; CHECK-NOT: br i1 %
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; CHECK: ret i32
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define i32 @branch_folded(i32* noalias nocapture readonly %b) {
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entry:
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br label %for.body
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for.body: ; preds = %for.inc, %entry
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%iv.0 = phi i64 [ 0, %entry ], [ %iv.1, %for.inc ]
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%r.0 = phi i32 [ 0, %entry ], [ %r.1, %for.inc ]
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%arrayidx1 = getelementptr inbounds [10 x i32], [10 x i32]* @known_constant, i64 0, i64 %iv.0
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%x1 = load i32, i32* %arrayidx1, align 4
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%cmp = icmp eq i32 %x1, 0
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%iv.1 = add nuw nsw i64 %iv.0, 1
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br i1 %cmp, label %if.then, label %for.inc
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if.then: ; preds = %for.body
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%arrayidx2 = getelementptr inbounds i32, i32* %b, i64 %iv.0
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%x2 = load i32, i32* %arrayidx2, align 4
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%add = add nsw i32 %x2, %r.0
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br label %for.inc
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for.inc: ; preds = %for.body, %if.then
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%r.1 = phi i32 [ %add, %if.then ], [ %x1, %for.body ]
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%exitcond = icmp eq i64 %iv.1, 10
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br i1 %exitcond, label %for.end, label %for.body
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for.end: ; preds = %for.inc
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ret i32 %r.1
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}
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; This test is similar to the previous one, but in this we use IV in comparison
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; (not a loaded value as we did there).
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; CHECK-LABEL: @branch_iv
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; CHECK-NOT: br i1 %
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; CHECK: ret i64
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define i64 @branch_iv(i64* noalias nocapture readonly %b) {
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entry:
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br label %for.body
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for.body: ; preds = %for.inc, %entry
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%indvars.iv = phi i64 [ 0, %entry ], [ %tmp3, %for.inc ]
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%r.030 = phi i64 [ 0, %entry ], [ %r.1, %for.inc ]
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%cmp3 = icmp eq i64 %indvars.iv, 5
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%tmp3 = add nuw nsw i64 %indvars.iv, 1
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br i1 %cmp3, label %if.then, label %for.inc
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if.then: ; preds = %for.body
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%arrayidx2 = getelementptr inbounds i64, i64* %b, i64 %tmp3
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%tmp1 = load i64, i64* %arrayidx2, align 4
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%add = add nsw i64 %tmp1, %r.030
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br label %for.inc
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for.inc: ; preds = %if.then, %for.body
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%r.1 = phi i64 [ %add, %if.then ], [ %r.030, %for.body ]
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%exitcond = icmp eq i64 %tmp3, 20
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br i1 %exitcond, label %for.end, label %for.body
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for.end: ; preds = %for.inc
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ret i64 %r.1
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}
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; Induction variables are often casted to another type, and that shouldn't
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; prevent us from folding branches. Tthis test specifically checks if we can
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; handle this. Other than thatm it's similar to the previous test.
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; CHECK-LABEL: @branch_iv_trunc
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; CHECK-NOT: br i1 %
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; CHECK: ret i32
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define i32 @branch_iv_trunc(i32* noalias nocapture readonly %b) {
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entry:
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br label %for.body
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for.body: ; preds = %for.inc, %entry
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%indvars.iv = phi i64 [ 0, %entry ], [ %tmp3, %for.inc ]
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%r.030 = phi i32 [ 0, %entry ], [ %r.1, %for.inc ]
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%tmp2 = trunc i64 %indvars.iv to i32
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%cmp3 = icmp eq i32 %tmp2, 5
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%tmp3 = add nuw nsw i64 %indvars.iv, 1
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br i1 %cmp3, label %if.then, label %for.inc
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if.then: ; preds = %for.body
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%arrayidx2 = getelementptr inbounds i32, i32* %b, i64 %tmp3
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%tmp1 = load i32, i32* %arrayidx2, align 4
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%add = add nsw i32 %tmp1, %r.030
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br label %for.inc
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for.inc: ; preds = %if.then, %for.body
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%r.1 = phi i32 [ %add, %if.then ], [ %r.030, %for.body ]
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%exitcond = icmp eq i64 %tmp3, 10
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br i1 %exitcond, label %for.end, label %for.body
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for.end: ; preds = %for.inc
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ret i32 %r.1
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}
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; Check that we don't crash when we analyze icmp with pointer-typed IV and a
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; pointer.
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; CHECK-LABEL: @ptr_cmp_crash
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; CHECK: ret void
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define void @ptr_cmp_crash() {
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entry:
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br label %while.body
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while.body:
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%iv.0 = phi i32* [ getelementptr inbounds ([10 x i32], [10 x i32]* @known_constant, i64 0, i64 0), %entry ], [ %iv.1, %while.body ]
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%iv.1 = getelementptr inbounds i32, i32* %iv.0, i64 1
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%exitcond = icmp eq i32* %iv.1, getelementptr inbounds ([10 x i32], [10 x i32]* @known_constant, i64 0, i64 9)
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br i1 %exitcond, label %loop.exit, label %while.body
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loop.exit:
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ret void
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}
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; Check that we don't crash when we analyze ptrtoint cast.
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; CHECK-LABEL: @ptrtoint_cast_crash
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; CHECK: ret void
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define void @ptrtoint_cast_crash(i8 * %a) {
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entry:
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%limit = getelementptr i8, i8* %a, i64 512
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br label %loop.body
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loop.body:
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%iv.0 = phi i8* [ %a, %entry ], [ %iv.1, %loop.body ]
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%cast = ptrtoint i8* %iv.0 to i64
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%iv.1 = getelementptr inbounds i8, i8* %iv.0, i64 1
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%exitcond = icmp ne i8* %iv.1, %limit
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br i1 %exitcond, label %loop.body, label %loop.exit
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loop.exit:
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ret void
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}
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; Loop unroller should be able to predict that a comparison would become
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; constant if the operands are pointers with the same base and constant
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; offsets.
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; We expect this loop to be unrolled, since most of its instructions would
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; become constant after it.
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; CHECK-LABEL: @ptr_cmp
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; CHECK-NOT: br i1 %
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; CHECK: ret i64
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define i64 @ptr_cmp(i8 * %a) {
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entry:
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%limit = getelementptr i8, i8* %a, i64 40
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%start.iv2 = getelementptr i8, i8* %a, i64 7
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br label %loop.body
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loop.body:
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%iv.0 = phi i8* [ %a, %entry ], [ %iv.1, %loop.body ]
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%iv2.0 = phi i8* [ %start.iv2, %entry ], [ %iv2.1, %loop.body ]
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%r.0 = phi i64 [ 0, %entry ], [ %r.1, %loop.body ]
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%cast = ptrtoint i8* %iv.0 to i64
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%cmp = icmp eq i8* %iv2.0, %iv.0
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%sub = sext i1 %cmp to i64
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%mul = mul i64 %sub, %cast
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%r.1 = add i64 %r.0, %mul
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%iv.1 = getelementptr inbounds i8, i8* %iv.0, i64 1
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%iv2.1 = getelementptr inbounds i8, i8* %iv2.0, i64 1
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%exitcond = icmp ne i8* %iv.1, %limit
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br i1 %exitcond, label %loop.body, label %loop.exit
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loop.exit:
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ret i64 %r.1
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}
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