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75d009930b
The register usage algorithm incorrectly treats instructions whose value is not used within the loop (e.g. those that do not produce a value). The algorithm first calculates the usages within the loop. It iterates over the instructions in order, and records at which instruction index each use ends (in fact, they're actually recorded against the next index, as this is when we want to delete them from the open intervals). The algorithm then iterates over the instructions again, adding each instruction in turn to a list of open intervals. Instructions are then removed from the list of open intervals when they occur in the list of uses ended at the current index. The problem is, instructions which are not used in the loop are skipped. However, although they aren't used, the last use of a value may have been recorded against that instruction index. In this case, the use is not deleted from the open intervals, which may then bump up the estimated register usage. This patch fixes the issue by simply moving the "is used" check after the loop which erases the uses at the current index. Differential Revision: https://reviews.llvm.org/D26554 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@286969 91177308-0d34-0410-b5e6-96231b3b80d8
140 lines
5.2 KiB
LLVM
140 lines
5.2 KiB
LLVM
; RUN: opt < %s -debug-only=loop-vectorize -loop-vectorize -vectorizer-maximize-bandwidth -O2 -mtriple=x86_64-unknown-linux -S 2>&1 | FileCheck %s
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; RUN: opt < %s -debug-only=loop-vectorize -loop-vectorize -vectorizer-maximize-bandwidth -O2 -mtriple=x86_64-unknown-linux -mattr=+avx512f -S 2>&1 | FileCheck %s --check-prefix=AVX512F
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; REQUIRES: asserts
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@a = global [1024 x i8] zeroinitializer, align 16
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@b = global [1024 x i8] zeroinitializer, align 16
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define i32 @foo() {
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; This function has a loop of SAD pattern. Here we check when VF = 16 the
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; register usage doesn't exceed 16.
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;
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; CHECK-LABEL: foo
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; CHECK: LV(REG): VF = 4
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; CHECK-NEXT: LV(REG): Found max usage: 4
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; CHECK: LV(REG): VF = 8
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; CHECK-NEXT: LV(REG): Found max usage: 7
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; CHECK: LV(REG): VF = 16
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; CHECK-NEXT: LV(REG): Found max usage: 13
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entry:
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br label %for.body
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for.cond.cleanup:
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%add.lcssa = phi i32 [ %add, %for.body ]
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ret i32 %add.lcssa
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for.body:
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%indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
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%s.015 = phi i32 [ 0, %entry ], [ %add, %for.body ]
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%arrayidx = getelementptr inbounds [1024 x i8], [1024 x i8]* @a, i64 0, i64 %indvars.iv
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%0 = load i8, i8* %arrayidx, align 1
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%conv = zext i8 %0 to i32
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%arrayidx2 = getelementptr inbounds [1024 x i8], [1024 x i8]* @b, i64 0, i64 %indvars.iv
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%1 = load i8, i8* %arrayidx2, align 1
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%conv3 = zext i8 %1 to i32
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%sub = sub nsw i32 %conv, %conv3
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%ispos = icmp sgt i32 %sub, -1
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%neg = sub nsw i32 0, %sub
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%2 = select i1 %ispos, i32 %sub, i32 %neg
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%add = add nsw i32 %2, %s.015
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%indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
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%exitcond = icmp eq i64 %indvars.iv.next, 1024
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br i1 %exitcond, label %for.cond.cleanup, label %for.body
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}
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define i32 @goo() {
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; For indvars.iv used in a computating chain only feeding into getelementptr or cmp,
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; it will not have vector version and the vector register usage will not exceed the
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; available vector register number.
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; CHECK-LABEL: goo
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; CHECK: LV(REG): VF = 4
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; CHECK-NEXT: LV(REG): Found max usage: 4
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; CHECK: LV(REG): VF = 8
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; CHECK-NEXT: LV(REG): Found max usage: 7
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; CHECK: LV(REG): VF = 16
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; CHECK-NEXT: LV(REG): Found max usage: 13
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entry:
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br label %for.body
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for.cond.cleanup: ; preds = %for.body
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%add.lcssa = phi i32 [ %add, %for.body ]
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ret i32 %add.lcssa
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for.body: ; preds = %for.body, %entry
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%indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
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%s.015 = phi i32 [ 0, %entry ], [ %add, %for.body ]
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%tmp1 = add nsw i64 %indvars.iv, 3
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%arrayidx = getelementptr inbounds [1024 x i8], [1024 x i8]* @a, i64 0, i64 %tmp1
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%tmp = load i8, i8* %arrayidx, align 1
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%conv = zext i8 %tmp to i32
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%tmp2 = add nsw i64 %indvars.iv, 2
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%arrayidx2 = getelementptr inbounds [1024 x i8], [1024 x i8]* @b, i64 0, i64 %tmp2
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%tmp3 = load i8, i8* %arrayidx2, align 1
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%conv3 = zext i8 %tmp3 to i32
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%sub = sub nsw i32 %conv, %conv3
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%ispos = icmp sgt i32 %sub, -1
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%neg = sub nsw i32 0, %sub
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%tmp4 = select i1 %ispos, i32 %sub, i32 %neg
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%add = add nsw i32 %tmp4, %s.015
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%indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
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%exitcond = icmp eq i64 %indvars.iv.next, 1024
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br i1 %exitcond, label %for.cond.cleanup, label %for.body
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}
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define i64 @bar(i64* nocapture %a) {
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; CHECK-LABEL: bar
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; CHECK: LV(REG): VF = 2
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; CHECK: LV(REG): Found max usage: 3
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;
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entry:
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br label %for.body
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for.cond.cleanup:
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%add2.lcssa = phi i64 [ %add2, %for.body ]
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ret i64 %add2.lcssa
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for.body:
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%i.012 = phi i64 [ 0, %entry ], [ %inc, %for.body ]
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%s.011 = phi i64 [ 0, %entry ], [ %add2, %for.body ]
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%arrayidx = getelementptr inbounds i64, i64* %a, i64 %i.012
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%0 = load i64, i64* %arrayidx, align 8
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%add = add nsw i64 %0, %i.012
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store i64 %add, i64* %arrayidx, align 8
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%add2 = add nsw i64 %add, %s.011
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%inc = add nuw nsw i64 %i.012, 1
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%exitcond = icmp eq i64 %inc, 1024
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br i1 %exitcond, label %for.cond.cleanup, label %for.body
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}
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@d = external global [0 x i64], align 8
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@e = external global [0 x i32], align 4
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@c = external global [0 x i32], align 4
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define void @hoo(i32 %n) {
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; For c[i] = e[d[i]] in the loop, e[d[i]] is not consecutive but its index %tmp can
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; be gathered into a vector. For VF == 16, the vector version of %tmp will be <16 x i64>
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; so the max usage of AVX512 vector register will be 2.
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; AVX512F-LABEL: bar
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; AVX512F: LV(REG): VF = 16
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; AVX512F: LV(REG): Found max usage: 2
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;
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entry:
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br label %for.body
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for.body: ; preds = %for.body, %entry
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%indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
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%arrayidx = getelementptr inbounds [0 x i64], [0 x i64]* @d, i64 0, i64 %indvars.iv
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%tmp = load i64, i64* %arrayidx, align 8
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%arrayidx1 = getelementptr inbounds [0 x i32], [0 x i32]* @e, i64 0, i64 %tmp
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%tmp1 = load i32, i32* %arrayidx1, align 4
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%arrayidx3 = getelementptr inbounds [0 x i32], [0 x i32]* @c, i64 0, i64 %indvars.iv
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store i32 %tmp1, i32* %arrayidx3, align 4
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%indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
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%exitcond = icmp eq i64 %indvars.iv.next, 10000
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br i1 %exitcond, label %for.end, label %for.body
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for.end: ; preds = %for.body
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ret void
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}
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