[llvm] r315992 - Improve clamp recognition in ValueTracking.
Nikolai Bozhenov via llvm-commits
llvm-commits at lists.llvm.org
Tue Oct 17 04:50:48 PDT 2017
Author: n.bozhenov
Date: Tue Oct 17 04:50:48 2017
New Revision: 315992
URL: http://llvm.org/viewvc/llvm-project?rev=315992&view=rev
Log:
Improve clamp recognition in ValueTracking.
Summary:
ValueTracking was recognizing not all variations of clamp. Swapping of
true value and false value of select was added to fix this problem. This
change breaks the canonical form of cmp inside the matchMinMax function,
that is why additional checks for compare predicates is needed. Added
corresponding test cases.
Reviewers: spatel
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D38531
Patch by: Artur Gainullin <artur.gainullin at intel.com>
Modified:
llvm/trunk/lib/Analysis/ValueTracking.cpp
llvm/trunk/test/Transforms/InstCombine/minmax-fold.ll
Modified: llvm/trunk/lib/Analysis/ValueTracking.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ValueTracking.cpp?rev=315992&r1=315991&r2=315992&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/ValueTracking.cpp (original)
+++ llvm/trunk/lib/Analysis/ValueTracking.cpp Tue Oct 17 04:50:48 2017
@@ -4083,6 +4083,14 @@ static SelectPatternResult matchMinMax(C
Value *CmpLHS, Value *CmpRHS,
Value *TrueVal, Value *FalseVal,
Value *&LHS, Value *&RHS) {
+ assert(!ICmpInst::isEquality(Pred) && "Expected not equality predicate only!");
+
+ // First, check if select has inverse order of what we will check below:
+ if (CmpRHS == FalseVal) {
+ std::swap(TrueVal, FalseVal);
+ Pred = CmpInst::getInversePredicate(Pred);
+ }
+
// Assume success. If there's no match, callers should not use these anyway.
LHS = TrueVal;
RHS = FalseVal;
@@ -4095,26 +4103,30 @@ static SelectPatternResult matchMinMax(C
// (X <s C1) ? C1 : SMIN(X, C2) ==> SMAX(SMIN(X, C2), C1)
if (match(FalseVal, m_SMin(m_Specific(CmpLHS), m_APInt(C2))) &&
- C1->slt(*C2) && Pred == CmpInst::ICMP_SLT)
+ C1->slt(*C2) &&
+ (Pred == CmpInst::ICMP_SLT || Pred == CmpInst::ICMP_SLE))
return {SPF_SMAX, SPNB_NA, false};
// (X >s C1) ? C1 : SMAX(X, C2) ==> SMIN(SMAX(X, C2), C1)
if (match(FalseVal, m_SMax(m_Specific(CmpLHS), m_APInt(C2))) &&
- C1->sgt(*C2) && Pred == CmpInst::ICMP_SGT)
+ C1->sgt(*C2) &&
+ (Pred == CmpInst::ICMP_SGT || Pred == CmpInst::ICMP_SGE))
return {SPF_SMIN, SPNB_NA, false};
// (X <u C1) ? C1 : UMIN(X, C2) ==> UMAX(UMIN(X, C2), C1)
if (match(FalseVal, m_UMin(m_Specific(CmpLHS), m_APInt(C2))) &&
- C1->ult(*C2) && Pred == CmpInst::ICMP_ULT)
+ C1->ult(*C2) &&
+ (Pred == CmpInst::ICMP_ULT || Pred == CmpInst::ICMP_ULE))
return {SPF_UMAX, SPNB_NA, false};
// (X >u C1) ? C1 : UMAX(X, C2) ==> UMIN(UMAX(X, C2), C1)
if (match(FalseVal, m_UMax(m_Specific(CmpLHS), m_APInt(C2))) &&
- C1->ugt(*C2) && Pred == CmpInst::ICMP_UGT)
+ C1->ugt(*C2) &&
+ (Pred == CmpInst::ICMP_UGT || Pred == CmpInst::ICMP_UGE))
return {SPF_UMIN, SPNB_NA, false};
}
- if (Pred != CmpInst::ICMP_SGT && Pred != CmpInst::ICMP_SLT)
+ if (!CmpInst::isSigned(Pred))
return {SPF_UNKNOWN, SPNB_NA, false};
// Z = X -nsw Y
@@ -4122,14 +4134,18 @@ static SelectPatternResult matchMinMax(C
// (X <s Y) ? 0 : Z ==> (Z <s 0) ? 0 : Z ==> SMAX(Z, 0)
if (match(TrueVal, m_Zero()) &&
match(FalseVal, m_NSWSub(m_Specific(CmpLHS), m_Specific(CmpRHS))))
- return {Pred == CmpInst::ICMP_SGT ? SPF_SMIN : SPF_SMAX, SPNB_NA, false};
+ return {(Pred == CmpInst::ICMP_SGT || Pred == CmpInst::ICMP_SGE) ? SPF_SMIN
+ : SPF_SMAX,
+ SPNB_NA, false};
// Z = X -nsw Y
// (X >s Y) ? Z : 0 ==> (Z >s 0) ? Z : 0 ==> SMAX(Z, 0)
// (X <s Y) ? Z : 0 ==> (Z <s 0) ? Z : 0 ==> SMIN(Z, 0)
if (match(FalseVal, m_Zero()) &&
match(TrueVal, m_NSWSub(m_Specific(CmpLHS), m_Specific(CmpRHS))))
- return {Pred == CmpInst::ICMP_SGT ? SPF_SMAX : SPF_SMIN, SPNB_NA, false};
+ return {(Pred == CmpInst::ICMP_SGT || Pred == CmpInst::ICMP_SGE) ? SPF_SMAX
+ : SPF_SMIN,
+ SPNB_NA, false};
if (!match(CmpRHS, m_APInt(C1)))
return {SPF_UNKNOWN, SPNB_NA, false};
@@ -4141,14 +4157,15 @@ static SelectPatternResult matchMinMax(C
// Is the sign bit set?
// (X <s 0) ? X : MAXVAL ==> (X >u MAXVAL) ? X : MAXVAL ==> UMAX
// (X <s 0) ? MAXVAL : X ==> (X >u MAXVAL) ? MAXVAL : X ==> UMIN
- if (Pred == CmpInst::ICMP_SLT && *C1 == 0 && C2->isMaxSignedValue())
+ if ((Pred == CmpInst::ICMP_SLT || Pred == CmpInst::ICMP_SLE) && *C1 == 0 &&
+ C2->isMaxSignedValue())
return {CmpLHS == TrueVal ? SPF_UMAX : SPF_UMIN, SPNB_NA, false};
// Is the sign bit clear?
// (X >s -1) ? MINVAL : X ==> (X <u MINVAL) ? MINVAL : X ==> UMAX
// (X >s -1) ? X : MINVAL ==> (X <u MINVAL) ? X : MINVAL ==> UMIN
- if (Pred == CmpInst::ICMP_SGT && C1->isAllOnesValue() &&
- C2->isMinSignedValue())
+ if ((Pred == CmpInst::ICMP_SGT || Pred == CmpInst::ICMP_SGE) &&
+ C1->isAllOnesValue() && C2->isMinSignedValue())
return {CmpLHS == FalseVal ? SPF_UMAX : SPF_UMIN, SPNB_NA, false};
}
@@ -4157,13 +4174,17 @@ static SelectPatternResult matchMinMax(C
// (X <s C) ? ~X : ~C ==> (~X >s ~C) ? ~X : ~C ==> SMAX(~X, ~C)
if (match(TrueVal, m_Not(m_Specific(CmpLHS))) &&
match(FalseVal, m_APInt(C2)) && ~(*C1) == *C2)
- return {Pred == CmpInst::ICMP_SGT ? SPF_SMIN : SPF_SMAX, SPNB_NA, false};
+ return {(Pred == CmpInst::ICMP_SGT || Pred == CmpInst::ICMP_SGE) ? SPF_SMIN
+ : SPF_SMAX,
+ SPNB_NA, false};
// (X >s C) ? ~C : ~X ==> (~X <s ~C) ? ~C : ~X ==> SMAX(~C, ~X)
// (X <s C) ? ~C : ~X ==> (~X >s ~C) ? ~C : ~X ==> SMIN(~C, ~X)
if (match(FalseVal, m_Not(m_Specific(CmpLHS))) &&
match(TrueVal, m_APInt(C2)) && ~(*C1) == *C2)
- return {Pred == CmpInst::ICMP_SGT ? SPF_SMAX : SPF_SMIN, SPNB_NA, false};
+ return {(Pred == CmpInst::ICMP_SGT || Pred == CmpInst::ICMP_SGE) ? SPF_SMAX
+ : SPF_SMIN,
+ SPNB_NA, false};
return {SPF_UNKNOWN, SPNB_NA, false};
}
Modified: llvm/trunk/test/Transforms/InstCombine/minmax-fold.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/minmax-fold.ll?rev=315992&r1=315991&r2=315992&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/minmax-fold.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/minmax-fold.ll Tue Oct 17 04:50:48 2017
@@ -404,8 +404,8 @@ define i32 @clamp_signed3(i32 %x) {
; CHECK-LABEL: @clamp_signed3(
; CHECK-NEXT: [[CMP2:%.*]] = icmp slt i32 [[X:%.*]], 255
; CHECK-NEXT: [[MIN:%.*]] = select i1 [[CMP2]], i32 [[X]], i32 255
-; CHECK-NEXT: [[CMP1:%.*]] = icmp sgt i32 [[X]], 15
-; CHECK-NEXT: [[R:%.*]] = select i1 [[CMP1]], i32 [[MIN]], i32 15
+; CHECK-NEXT: [[TMP1:%.*]] = icmp sgt i32 [[MIN]], 15
+; CHECK-NEXT: [[R:%.*]] = select i1 [[TMP1]], i32 [[MIN]], i32 15
; CHECK-NEXT: ret i32 [[R]]
;
%cmp2 = icmp slt i32 %x, 255
@@ -421,8 +421,8 @@ define i32 @clamp_signed4(i32 %x) {
; CHECK-LABEL: @clamp_signed4(
; CHECK-NEXT: [[CMP2:%.*]] = icmp sgt i32 [[X:%.*]], 15
; CHECK-NEXT: [[MAX:%.*]] = select i1 [[CMP2]], i32 [[X]], i32 15
-; CHECK-NEXT: [[CMP1:%.*]] = icmp slt i32 [[X]], 255
-; CHECK-NEXT: [[R:%.*]] = select i1 [[CMP1]], i32 [[MAX]], i32 255
+; CHECK-NEXT: [[TMP1:%.*]] = icmp slt i32 [[MAX]], 255
+; CHECK-NEXT: [[R:%.*]] = select i1 [[TMP1]], i32 [[MAX]], i32 255
; CHECK-NEXT: ret i32 [[R]]
;
%cmp2 = icmp sgt i32 %x, 15
@@ -472,8 +472,8 @@ define i32 @clamp_unsigned3(i32 %x) {
; CHECK-LABEL: @clamp_unsigned3(
; CHECK-NEXT: [[CMP2:%.*]] = icmp ult i32 [[X:%.*]], 255
; CHECK-NEXT: [[MIN:%.*]] = select i1 [[CMP2]], i32 [[X]], i32 255
-; CHECK-NEXT: [[CMP1:%.*]] = icmp ugt i32 [[X]], 15
-; CHECK-NEXT: [[R:%.*]] = select i1 [[CMP1]], i32 [[MIN]], i32 15
+; CHECK-NEXT: [[TMP1:%.*]] = icmp ugt i32 [[MIN]], 15
+; CHECK-NEXT: [[R:%.*]] = select i1 [[TMP1]], i32 [[MIN]], i32 15
; CHECK-NEXT: ret i32 [[R]]
;
%cmp2 = icmp ult i32 %x, 255
@@ -489,8 +489,8 @@ define i32 @clamp_unsigned4(i32 %x) {
; CHECK-LABEL: @clamp_unsigned4(
; CHECK-NEXT: [[CMP2:%.*]] = icmp ugt i32 [[X:%.*]], 15
; CHECK-NEXT: [[MAX:%.*]] = select i1 [[CMP2]], i32 [[X]], i32 15
-; CHECK-NEXT: [[CMP1:%.*]] = icmp ult i32 [[X]], 255
-; CHECK-NEXT: [[R:%.*]] = select i1 [[CMP1]], i32 [[MAX]], i32 255
+; CHECK-NEXT: [[TMP1:%.*]] = icmp ult i32 [[MAX]], 255
+; CHECK-NEXT: [[R:%.*]] = select i1 [[TMP1]], i32 [[MAX]], i32 255
; CHECK-NEXT: ret i32 [[R]]
;
%cmp2 = icmp ugt i32 %x, 15
@@ -523,8 +523,8 @@ define i32 @clamp_check_for_no_infinite_
; CHECK-LABEL: @clamp_check_for_no_infinite_loop2(
; CHECK-NEXT: [[CMP1:%.*]] = icmp sgt i32 [[I:%.*]], -255
; CHECK-NEXT: [[SEL1:%.*]] = select i1 [[CMP1]], i32 [[I]], i32 -255
-; CHECK-NEXT: [[CMP2:%.*]] = icmp slt i32 [[I]], 0
-; CHECK-NEXT: [[RES:%.*]] = select i1 [[CMP2]], i32 [[SEL1]], i32 0
+; CHECK-NEXT: [[TMP1:%.*]] = icmp slt i32 [[SEL1]], 0
+; CHECK-NEXT: [[RES:%.*]] = select i1 [[TMP1]], i32 [[SEL1]], i32 0
; CHECK-NEXT: ret i32 [[RES]]
;
%cmp1 = icmp sgt i32 %i, -255
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