diff options
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp | 18 | ||||
| -rw-r--r-- | llvm/test/Transforms/InstCombine/saturating-add-sub.ll | 32 |
2 files changed, 27 insertions, 23 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp index 0e9d6f05275..d153c848d38 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp @@ -695,22 +695,30 @@ static Value *canonicalizeSaturatedAdd(ICmpInst *Cmp, Value *TVal, Value *FVal, return Builder.CreateSelect(NewCmp, FVal, TVal); } - // Canonicalize to 'ULT' to simplify matching below. + // Match unsigned saturated add of 2 variables with an unnecessary 'not'. + // There are 8 commuted variants. + // Canonicalize -1 (saturated result) to true value of the select. + if (match(FVal, m_AllOnes())) { + std::swap(TVal, FVal); + std::swap(Cmp0, Cmp1); + } + if (!match(TVal, m_AllOnes())) + return nullptr; + + // Canonicalize predicate to 'ULT'. if (Pred == ICmpInst::ICMP_UGT) { Pred = ICmpInst::ICMP_ULT; std::swap(Cmp0, Cmp1); } - if (Pred != ICmpInst::ICMP_ULT) return nullptr; // Match unsigned saturated add of 2 variables with an unnecessary 'not'. - // TODO: There are more variations of this pattern. Value *Y; - if (match(TVal, m_AllOnes()) && match(Cmp0, m_Not(m_Value(X))) && + if (match(Cmp0, m_Not(m_Value(X))) && match(FVal, m_c_Add(m_Specific(X), m_Value(Y))) && Y == Cmp1) { // Change the comparison to use the sum (false value of the select). That is - // the canonical pattern match form for uadd.with.overflow and eliminates a + // a canonical pattern match form for uadd.with.overflow and eliminates a // use of the 'not' op: // (~X u< Y) ? -1 : (X + Y) --> ((X + Y) u< Y) ? -1 : (X + Y) // (~X u< Y) ? -1 : (Y + X) --> ((Y + X) u< Y) ? -1 : (Y + X) diff --git a/llvm/test/Transforms/InstCombine/saturating-add-sub.ll b/llvm/test/Transforms/InstCombine/saturating-add-sub.ll index da3daecf393..fa55db931d0 100644 --- a/llvm/test/Transforms/InstCombine/saturating-add-sub.ll +++ b/llvm/test/Transforms/InstCombine/saturating-add-sub.ll @@ -706,11 +706,10 @@ define <2 x i32> @uadd_sat_ugt_commute_add(<2 x i32> %xp, <2 x i32> %yp) { define i32 @uadd_sat_commute_select(i32 %x, i32 %yp) { ; CHECK-LABEL: @uadd_sat_commute_select( ; CHECK-NEXT: [[Y:%.*]] = sdiv i32 [[YP:%.*]], 2442 -; CHECK-NEXT: [[NOTX:%.*]] = xor i32 [[X:%.*]], -1 -; CHECK-NEXT: [[A:%.*]] = add i32 [[Y]], [[X]] -; CHECK-NEXT: [[C:%.*]] = icmp ult i32 [[Y]], [[NOTX]] -; CHECK-NEXT: [[R:%.*]] = select i1 [[C]], i32 [[A]], i32 -1 -; CHECK-NEXT: ret i32 [[R]] +; CHECK-NEXT: [[A:%.*]] = add i32 [[Y]], [[X:%.*]] +; CHECK-NEXT: [[TMP1:%.*]] = icmp ult i32 [[A]], [[Y]] +; CHECK-NEXT: [[TMP2:%.*]] = select i1 [[TMP1]], i32 -1, i32 [[A]] +; CHECK-NEXT: ret i32 [[TMP2]] ; %y = sdiv i32 %yp, 2442 ; thwart complexity-based-canonicalization %notx = xor i32 %x, -1 @@ -724,11 +723,10 @@ define i32 @uadd_sat_commute_select_commute_add(i32 %xp, i32 %yp) { ; CHECK-LABEL: @uadd_sat_commute_select_commute_add( ; CHECK-NEXT: [[X:%.*]] = urem i32 42, [[XP:%.*]] ; CHECK-NEXT: [[Y:%.*]] = sdiv i32 [[YP:%.*]], 2442 -; CHECK-NEXT: [[NOTX:%.*]] = xor i32 [[X]], -1 ; CHECK-NEXT: [[A:%.*]] = add nsw i32 [[X]], [[Y]] -; CHECK-NEXT: [[C:%.*]] = icmp ult i32 [[Y]], [[NOTX]] -; CHECK-NEXT: [[R:%.*]] = select i1 [[C]], i32 [[A]], i32 -1 -; CHECK-NEXT: ret i32 [[R]] +; CHECK-NEXT: [[TMP1:%.*]] = icmp ult i32 [[A]], [[Y]] +; CHECK-NEXT: [[TMP2:%.*]] = select i1 [[TMP1]], i32 -1, i32 [[A]] +; CHECK-NEXT: ret i32 [[TMP2]] ; %x = urem i32 42, %xp ; thwart complexity-based-canonicalization %y = sdiv i32 %yp, 2442 ; thwart complexity-based-canonicalization @@ -741,11 +739,10 @@ define i32 @uadd_sat_commute_select_commute_add(i32 %xp, i32 %yp) { define <2 x i32> @uadd_sat_commute_select_ugt(<2 x i32> %x, <2 x i32> %y) { ; CHECK-LABEL: @uadd_sat_commute_select_ugt( -; CHECK-NEXT: [[NOTX:%.*]] = xor <2 x i32> [[X:%.*]], <i32 -1, i32 -1> -; CHECK-NEXT: [[A:%.*]] = add <2 x i32> [[Y:%.*]], [[X]] -; CHECK-NEXT: [[C:%.*]] = icmp ugt <2 x i32> [[NOTX]], [[Y]] -; CHECK-NEXT: [[R:%.*]] = select <2 x i1> [[C]], <2 x i32> [[A]], <2 x i32> <i32 -1, i32 -1> -; CHECK-NEXT: ret <2 x i32> [[R]] +; CHECK-NEXT: [[A:%.*]] = add <2 x i32> [[Y:%.*]], [[X:%.*]] +; CHECK-NEXT: [[TMP1:%.*]] = icmp ult <2 x i32> [[A]], [[Y]] +; CHECK-NEXT: [[TMP2:%.*]] = select <2 x i1> [[TMP1]], <2 x i32> <i32 -1, i32 -1>, <2 x i32> [[A]] +; CHECK-NEXT: ret <2 x i32> [[TMP2]] ; %notx = xor <2 x i32> %x, <i32 -1, i32 -1> %a = add <2 x i32> %y, %x @@ -757,11 +754,10 @@ define <2 x i32> @uadd_sat_commute_select_ugt(<2 x i32> %x, <2 x i32> %y) { define i32 @uadd_sat_commute_select_ugt_commute_add(i32 %xp, i32 %y) { ; CHECK-LABEL: @uadd_sat_commute_select_ugt_commute_add( ; CHECK-NEXT: [[X:%.*]] = srem i32 42, [[XP:%.*]] -; CHECK-NEXT: [[NOTX:%.*]] = xor i32 [[X]], -1 ; CHECK-NEXT: [[A:%.*]] = add i32 [[X]], [[Y:%.*]] -; CHECK-NEXT: [[C:%.*]] = icmp ugt i32 [[NOTX]], [[Y]] -; CHECK-NEXT: [[R:%.*]] = select i1 [[C]], i32 [[A]], i32 -1 -; CHECK-NEXT: ret i32 [[R]] +; CHECK-NEXT: [[TMP1:%.*]] = icmp ult i32 [[A]], [[Y]] +; CHECK-NEXT: [[TMP2:%.*]] = select i1 [[TMP1]], i32 -1, i32 [[A]] +; CHECK-NEXT: ret i32 [[TMP2]] ; %x = srem i32 42, %xp ; thwart complexity-based-canonicalization %notx = xor i32 %x, -1 |
