[llvm] r354277 - Revert "[InstCombine] reduce even more unsigned saturated add with 'not' op"
Sanjay Patel via llvm-commits
llvm-commits at lists.llvm.org
Mon Feb 18 08:04:22 PST 2019
Author: spatel
Date: Mon Feb 18 08:04:22 2019
New Revision: 354277
URL: http://llvm.org/viewvc/llvm-project?rev=354277&view=rev
Log:
Revert "[InstCombine] reduce even more unsigned saturated add with 'not' op"
This reverts commit 079b610c29b4a428b3ae7b64dbac0378facf6632.
Bots are failing after this change on a stage 2 compile of clang.
Modified:
llvm/trunk/lib/Transforms/InstCombine/InstCombineSelect.cpp
llvm/trunk/test/Transforms/InstCombine/saturating-add-sub.ll
Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineSelect.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineSelect.cpp?rev=354277&r1=354276&r2=354277&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineSelect.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineSelect.cpp Mon Feb 18 08:04:22 2019
@@ -680,46 +680,25 @@ static Value *canonicalizeSaturatedAdd(I
if (!Cmp->hasOneUse())
return nullptr;
+ // Canonicalize to 'ULT' to simplify matching below.
Value *Cmp0 = Cmp->getOperand(0);
Value *Cmp1 = Cmp->getOperand(1);
-
- // Match unsigned saturated add with constant.
- Value *X;
- const APInt *C, *CmpC;
- if (match(TVal, m_Add(m_Value(X), m_APInt(C))) && X == Cmp0 &&
- match(Cmp1, m_APInt(CmpC)) && *CmpC == ~*C) {
- // Commute compare predicate and select operands. The backend is expecting
- // this form (-1 is true value). If this changes, the backend must be
- // updated too:
- // (X u< ~C) ? (X + C) : -1 --> (X u> ~C) ? -1 : (X + C)
- Value *NewCmp = Builder.CreateICmp(ICmpInst::ICMP_UGT, X, Cmp1);
- return Builder.CreateSelect(NewCmp, FVal, TVal);
- }
-
- // 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'.
ICmpInst::Predicate Pred = Cmp->getPredicate();
if (Pred == ICmpInst::ICMP_UGT) {
Pred = ICmpInst::ICMP_ULT;
std::swap(Cmp0, Cmp1);
}
+
if (Pred != ICmpInst::ICMP_ULT)
return nullptr;
- Value *Y;
- if (match(Cmp0, m_Not(m_Value(X))) &&
+ // Match unsigned saturated add of 2 variables with an unnecessary 'not'.
+ // TODO: There are more variations of this pattern.
+ Value *X, *Y;
+ if (match(TVal, m_AllOnes()) && 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
- // a canonical pattern match form for uadd.with.overflow and eliminates a
+ // the 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)
@@ -727,6 +706,16 @@ static Value *canonicalizeSaturatedAdd(I
return Builder.CreateSelect(NewCmp, TVal, FVal);
}
+ // Match unsigned saturated add with constant.
+ const APInt *C, *CmpC;
+ if (match(TVal, m_Add(m_Value(X), m_APInt(C))) && X == Cmp0 &&
+ match(FVal, m_AllOnes()) && match(Cmp1, m_APInt(CmpC)) && *CmpC == ~*C) {
+ // Commute compare predicate and select operands:
+ // (X u< ~C) ? (X + C) : -1 --> (X u> ~C) ? -1 : (X + C)
+ Value *NewCmp = Builder.CreateICmp(ICmpInst::ICMP_UGT, X, Cmp1);
+ return Builder.CreateSelect(NewCmp, FVal, TVal);
+ }
+
return nullptr;
}
Modified: llvm/trunk/test/Transforms/InstCombine/saturating-add-sub.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/saturating-add-sub.ll?rev=354277&r1=354276&r2=354277&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/saturating-add-sub.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/saturating-add-sub.ll Mon Feb 18 08:04:22 2019
@@ -706,10 +706,11 @@ define <2 x i32> @uadd_sat_ugt_commute_a
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: [[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]]
+; 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]]
;
%y = sdiv i32 %yp, 2442 ; thwart complexity-based-canonicalization
%notx = xor i32 %x, -1
@@ -723,10 +724,11 @@ define i32 @uadd_sat_commute_select_comm
; 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: [[TMP1:%.*]] = icmp ult i32 [[A]], [[Y]]
-; CHECK-NEXT: [[TMP2:%.*]] = select i1 [[TMP1]], i32 -1, i32 [[A]]
-; CHECK-NEXT: ret i32 [[TMP2]]
+; CHECK-NEXT: [[C:%.*]] = icmp ult i32 [[Y]], [[NOTX]]
+; CHECK-NEXT: [[R:%.*]] = select i1 [[C]], i32 [[A]], i32 -1
+; CHECK-NEXT: ret i32 [[R]]
;
%x = urem i32 42, %xp ; thwart complexity-based-canonicalization
%y = sdiv i32 %yp, 2442 ; thwart complexity-based-canonicalization
@@ -739,10 +741,11 @@ define i32 @uadd_sat_commute_select_comm
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: [[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]]
+; 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]]
;
%notx = xor <2 x i32> %x, <i32 -1, i32 -1>
%a = add <2 x i32> %y, %x
@@ -754,10 +757,11 @@ define <2 x i32> @uadd_sat_commute_selec
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: [[TMP1:%.*]] = icmp ult i32 [[A]], [[Y]]
-; CHECK-NEXT: [[TMP2:%.*]] = select i1 [[TMP1]], i32 -1, i32 [[A]]
-; CHECK-NEXT: ret i32 [[TMP2]]
+; CHECK-NEXT: [[C:%.*]] = icmp ugt i32 [[NOTX]], [[Y]]
+; CHECK-NEXT: [[R:%.*]] = select i1 [[C]], i32 [[A]], i32 -1
+; CHECK-NEXT: ret i32 [[R]]
;
%x = srem i32 42, %xp ; thwart complexity-based-canonicalization
%notx = xor i32 %x, -1
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