Add another variant of this test which found a place where

CodeGen's ComputeMaskedBits was being over-conservative when computing
bits for an ADD.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@101963 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman 2010-04-21 00:19:28 +00:00
parent d6139425f5
commit bc7588eb68
2 changed files with 45 additions and 1 deletions

View File

@ -1917,7 +1917,8 @@ void SelectionDAG::ComputeMaskedBits(SDValue Op, const APInt &Mask,
// Output known-0 bits are known if clear or set in both the low clear bits
// common to both LHS & RHS. For example, 8+(X<<3) is known to have the
// low 3 bits clear.
APInt Mask2 = APInt::getLowBitsSet(BitWidth, Mask.countTrailingOnes());
APInt Mask2 = APInt::getLowBitsSet(BitWidth,
BitWidth - Mask.countLeadingZeros());
ComputeMaskedBits(Op.getOperand(0), Mask2, KnownZero2, KnownOne2, Depth+1);
assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
unsigned KnownZeroOut = KnownZero2.countTrailingOnes();

View File

@ -45,3 +45,46 @@ bb: ; preds = %bb, %bb.nph
return: ; preds = %bb
ret void
}
; CHECK: test1:
; CHECK: movl %{{.*}}, (%rdi,%rcx,4)
; CHECK: movl %{{.*}}, 8(%rdi,%rcx,4)
; CHECK: movl %{{.*}}, 4(%rdi,%rcx,4)
; CHECK: movl %{{.*}}, 12(%rdi,%rcx,4)
define void @test1(i32* nocapture %array, i32 %r0, i8 signext %k, i8 signext %i0) nounwind {
bb.nph:
br label %for.body
for.body: ; preds = %for.body, %bb.nph
%j.065 = phi i8 [ 0, %bb.nph ], [ %inc52, %for.body ] ; <i8> [#uses=1]
%i0.addr.064 = phi i8 [ %i0, %bb.nph ], [ %add, %for.body ] ; <i8> [#uses=3]
%k.addr.163 = phi i8 [ %k, %bb.nph ], [ %inc.k.addr.1, %for.body ] ; <i8> [#uses=1]
%cmp5 = icmp slt i8 %i0.addr.064, 4 ; <i1> [#uses=1]
%cond = select i1 %cmp5, i8 %i0.addr.064, i8 0 ; <i8> [#uses=2]
%cmp12 = icmp eq i8 %i0.addr.064, 4 ; <i1> [#uses=1]
%inc = zext i1 %cmp12 to i8 ; <i8> [#uses=1]
%inc.k.addr.1 = add i8 %inc, %k.addr.163 ; <i8> [#uses=2]
%mul = shl i8 %cond, 2 ; <i8> [#uses=1]
%mul22 = shl i8 %inc.k.addr.1, 4 ; <i8> [#uses=1]
%add23 = add i8 %mul22, %mul ; <i8> [#uses=1]
%idxprom = zext i8 %add23 to i64 ; <i64> [#uses=4]
%arrayidx = getelementptr inbounds i32* %array, i64 %idxprom ; <i32*> [#uses=1]
store i32 %r0, i32* %arrayidx
%add3356 = or i64 %idxprom, 2 ; <i64> [#uses=1]
%arrayidx36 = getelementptr inbounds i32* %array, i64 %add3356 ; <i32*> [#uses=1]
store i32 %r0, i32* %arrayidx36
%add4058 = or i64 %idxprom, 1 ; <i64> [#uses=1]
%arrayidx43 = getelementptr inbounds i32* %array, i64 %add4058 ; <i32*> [#uses=1]
store i32 %r0, i32* %arrayidx43
%add4760 = or i64 %idxprom, 3 ; <i64> [#uses=1]
%arrayidx50 = getelementptr inbounds i32* %array, i64 %add4760 ; <i32*> [#uses=1]
store i32 %r0, i32* %arrayidx50
%inc52 = add nsw i8 %j.065, 1 ; <i8> [#uses=2]
%add = add i8 %cond, 1 ; <i8> [#uses=1]
%exitcond = icmp eq i8 %inc52, 32 ; <i1> [#uses=1]
br i1 %exitcond, label %for.end, label %for.body
for.end: ; preds = %for.body
ret void
}