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4781d8ee1c
Fixes PR13371: indvars pass incorrectly substitutes 'undef' values. I do not like this fix. It's needed until/unless the meaning of undef changes. It attempts to be complete according to the IR spec, but I don't have much confidence in the implementation given the difficulty testing undefined behavior. Worse, this invalidates some of my hard-fought work on indvars and LSR to optimize pointer induction variables. It results benchmark regressions, which I'll track internally. On x86_64 no LTO I see: -3% huffbench -3% 400.perlbench -8% fhourstones My only suggestion for recovering is to change the meaning of undef. If we could trust an arbitrary instruction to produce a some real value that can be manipulated (e.g. incremented) according to non-undef rules, then this case could be easily handled with SCEV. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160421 91177308-0d34-0410-b5e6-96231b3b80d8
234 lines
6.6 KiB
LLVM
234 lines
6.6 KiB
LLVM
; RUN: opt < %s -indvars -S | FileCheck %s
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;
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; Make sure that indvars can perform LFTR without a canonical IV.
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target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
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; Perform LFTR using the original pointer-type IV.
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; for(char* p = base; p < base + n; ++p) {
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; *p = p-base;
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; }
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define void @ptriv(i8* %base, i32 %n) nounwind {
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entry:
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%idx.ext = sext i32 %n to i64
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%add.ptr = getelementptr inbounds i8* %base, i64 %idx.ext
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%cmp1 = icmp ult i8* %base, %add.ptr
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br i1 %cmp1, label %for.body, label %for.end
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; CHECK: for.body:
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; CHECK: phi i8*
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; CHECK-NOT: phi
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; CHECK-NOT: add
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; CHECK: icmp ne i8*
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; CHECK: br i1
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for.body:
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%p.02 = phi i8* [ %base, %entry ], [ %incdec.ptr, %for.body ]
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; cruft to make the IV useful
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%sub.ptr.lhs.cast = ptrtoint i8* %p.02 to i64
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%sub.ptr.rhs.cast = ptrtoint i8* %base to i64
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%sub.ptr.sub = sub i64 %sub.ptr.lhs.cast, %sub.ptr.rhs.cast
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%conv = trunc i64 %sub.ptr.sub to i8
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store i8 %conv, i8* %p.02
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%incdec.ptr = getelementptr inbounds i8* %p.02, i32 1
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%cmp = icmp ult i8* %incdec.ptr, %add.ptr
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br i1 %cmp, label %for.body, label %for.end
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for.end:
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ret void
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}
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; It would be nice if SCEV and any loop analysis could assume that
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; preheaders exist. Unfortunately it is not always the case. This test
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; checks that SCEVExpander can handle an outer loop that has not yet
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; been simplified. As a result, the inner loop's exit test will not be
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; rewritten.
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define void @expandOuterRecurrence(i32 %arg) nounwind {
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entry:
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%sub1 = sub nsw i32 %arg, 1
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%cmp1 = icmp slt i32 0, %sub1
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br i1 %cmp1, label %outer, label %exit
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outer:
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%i = phi i32 [ 0, %entry ], [ %i.inc, %outer.inc ]
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%sub2 = sub nsw i32 %arg, %i
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%sub3 = sub nsw i32 %sub2, 1
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%cmp2 = icmp slt i32 0, %sub3
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br i1 %cmp2, label %inner.ph, label %outer.inc
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inner.ph:
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br label %inner
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; CHECK: inner:
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; CHECK: icmp slt
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; CHECK: br i1
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inner:
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%j = phi i32 [ 0, %inner.ph ], [ %j.inc, %inner ]
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%j.inc = add nsw i32 %j, 1
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%cmp3 = icmp slt i32 %j.inc, %sub3
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br i1 %cmp3, label %inner, label %outer.inc
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; CHECK: outer.inc:
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; CHECK: icmp ne
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; CHECK: br i1
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outer.inc:
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%i.inc = add nsw i32 %i, 1
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%cmp4 = icmp slt i32 %i.inc, %sub1
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br i1 %cmp4, label %outer, label %exit
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exit:
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ret void
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}
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; Force SCEVExpander to look for an existing well-formed phi.
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; Perform LFTR without generating extra preheader code.
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define void @guardedloop([0 x double]* %matrix, [0 x double]* %vector,
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i32 %irow, i32 %ilead) nounwind {
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; CHECK: entry:
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; CHECK-NOT: zext
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; CHECK-NOT: add
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; CHECK: loop:
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; CHECK: phi i64
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; CHECK: phi i64
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; CHECK-NOT: phi
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; CHECK: icmp ne
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; CHECK: br i1
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entry:
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%cmp = icmp slt i32 1, %irow
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br i1 %cmp, label %loop, label %return
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loop:
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%rowidx = phi i32 [ 0, %entry ], [ %row.inc, %loop ]
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%i = phi i32 [ 0, %entry ], [ %i.inc, %loop ]
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%diagidx = add nsw i32 %rowidx, %i
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%diagidxw = sext i32 %diagidx to i64
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%matrixp = getelementptr inbounds [0 x double]* %matrix, i32 0, i64 %diagidxw
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%v1 = load double* %matrixp
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%iw = sext i32 %i to i64
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%vectorp = getelementptr inbounds [0 x double]* %vector, i32 0, i64 %iw
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%v2 = load double* %vectorp
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%row.inc = add nsw i32 %rowidx, %ilead
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%i.inc = add nsw i32 %i, 1
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%cmp196 = icmp slt i32 %i.inc, %irow
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br i1 %cmp196, label %loop, label %return
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return:
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ret void
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}
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; Avoid generating extra code to materialize a trip count. Skip LFTR.
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define void @unguardedloop([0 x double]* %matrix, [0 x double]* %vector,
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i32 %irow, i32 %ilead) nounwind {
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entry:
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br label %loop
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; CHECK: entry:
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; CHECK-NOT: zext
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; CHECK-NOT: add
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; CHECK: loop:
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; CHECK: phi i64
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; CHECK: phi i64
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; CHECK-NOT: phi
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; CHECK: icmp slt
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; CHECK: br i1
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loop:
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%rowidx = phi i32 [ 0, %entry ], [ %row.inc, %loop ]
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%i = phi i32 [ 0, %entry ], [ %i.inc, %loop ]
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%diagidx = add nsw i32 %rowidx, %i
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%diagidxw = sext i32 %diagidx to i64
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%matrixp = getelementptr inbounds [0 x double]* %matrix, i32 0, i64 %diagidxw
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%v1 = load double* %matrixp
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%iw = sext i32 %i to i64
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%vectorp = getelementptr inbounds [0 x double]* %vector, i32 0, i64 %iw
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%v2 = load double* %vectorp
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%row.inc = add nsw i32 %rowidx, %ilead
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%i.inc = add nsw i32 %i, 1
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%cmp196 = icmp slt i32 %i.inc, %irow
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br i1 %cmp196, label %loop, label %return
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return:
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ret void
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}
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; Remove %i which is only used by the exit test.
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; Verify that SCEV can still compute a backedge count from the sign
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; extended %n, used for pointer comparison by LFTR.
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;
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; TODO: Fix for PR13371 currently makes this impossible. See
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; IndVarSimplify.cpp hasConcreteDef(). We may want to change to undef rules.
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define void @geplftr(i8* %base, i32 %x, i32 %y, i32 %n) nounwind {
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entry:
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%x.ext = sext i32 %x to i64
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%add.ptr = getelementptr inbounds i8* %base, i64 %x.ext
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%y.ext = sext i32 %y to i64
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%add.ptr10 = getelementptr inbounds i8* %add.ptr, i64 %y.ext
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%lim = add i32 %x, %n
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%cmp.ph = icmp ult i32 %x, %lim
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br i1 %cmp.ph, label %loop, label %exit
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; CHECK: @geplftr
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; CHECK: loop:
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; CHECK: phi i8*
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; DISABLE-NOT: phi // This check is currently disabled
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; CHECK: getelementptr
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; CHECK: store
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; DISABLE: icmp ne i8* // This check is currently disabled
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; CHECK: br i1
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loop:
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%i = phi i32 [ %x, %entry ], [ %inc, %loop ]
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%aptr = phi i8* [ %add.ptr10, %entry ], [ %incdec.ptr, %loop ]
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%incdec.ptr = getelementptr inbounds i8* %aptr, i32 1
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store i8 3, i8* %aptr
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%inc = add i32 %i, 1
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%cmp = icmp ult i32 %inc, %lim
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br i1 %cmp, label %loop, label %exit
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exit:
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ret void
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}
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; Exercise backedge taken count verification with a never-taken loop.
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define void @nevertaken() nounwind uwtable ssp {
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entry:
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br label %loop
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; CHECK: @nevertaken
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; CHECK: loop:
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; CHECK-NOT: phi
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; CHECK-NOT: add
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; CHECK-NOT: icmp
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; CHECK: exit:
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loop:
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%i = phi i32 [ 0, %entry ], [ %inc, %loop ]
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%inc = add nsw i32 %i, 1
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%cmp = icmp sle i32 %inc, 0
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br i1 %cmp, label %loop, label %exit
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exit:
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ret void
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}
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; Test LFTR on an IV whose recurrence start is a non-unit pointer type.
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define void @aryptriv([256 x i8]* %base, i32 %n) nounwind {
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entry:
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%ivstart = getelementptr inbounds [256 x i8]* %base, i32 0, i32 0
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%ivend = getelementptr inbounds [256 x i8]* %base, i32 0, i32 %n
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%cmp.ph = icmp ult i8* %ivstart, %ivend
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br i1 %cmp.ph, label %loop, label %exit
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; CHECK: loop:
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; CHECK: phi i8*
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; CHECK-NOT: phi
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; CHECK: getelementptr
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; CHECK: store
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; CHECK: icmp ne i8*
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; CHECK: br i1
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loop:
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%aptr = phi i8* [ %ivstart, %entry ], [ %incdec.ptr, %loop ]
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%incdec.ptr = getelementptr inbounds i8* %aptr, i32 1
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store i8 3, i8* %aptr
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%cmp = icmp ult i8* %incdec.ptr, %ivend
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br i1 %cmp, label %loop, label %exit
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exit:
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ret void
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}
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