[llvm-commits] [llvm] r91814 - in /llvm/trunk: lib/Transforms/Scalar/InstructionCombining.cpp test/Transforms/InstCombine/select.ll
Chris Lattner
sabre at nondot.org
Sun Dec 20 22:03:06 PST 2009
Author: lattner
Date: Mon Dec 21 00:03:05 2009
New Revision: 91814
URL: http://llvm.org/viewvc/llvm-project?rev=91814&view=rev
Log:
give instcombine some helper functions for matching MIN and MAX, and
implement some optimizations for MIN(MIN()) and MAX(MAX()) and
MIN(MAX()) etc. This substantially improves the code in PR5822 but
doesn't kick in much elsewhere. 2 max's were optimized in
pairlocalalign and one in smg2000.
Modified:
llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp
llvm/trunk/test/Transforms/InstCombine/select.ll
Modified: llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp?rev=91814&r1=91813&r2=91814&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp Mon Dec 21 00:03:05 2009
@@ -75,6 +75,15 @@
STATISTIC(NumDeadStore, "Number of dead stores eliminated");
STATISTIC(NumSunkInst , "Number of instructions sunk");
+/// SelectPatternFlavor - We can match a variety of different patterns for
+/// select operations.
+enum SelectPatternFlavor {
+ SPF_UNKNOWN = 0,
+ SPF_SMIN, SPF_UMIN,
+ SPF_SMAX, SPF_UMAX
+ //SPF_ABS - TODO.
+};
+
namespace {
/// InstCombineWorklist - This is the worklist management logic for
/// InstCombine.
@@ -281,6 +290,9 @@
Instruction *FoldSelectOpOp(SelectInst &SI, Instruction *TI,
Instruction *FI);
Instruction *FoldSelectIntoOp(SelectInst &SI, Value*, Value*);
+ Instruction *FoldSPFofSPF(Instruction *Inner, SelectPatternFlavor SPF1,
+ Value *A, Value *B, Instruction &Outer,
+ SelectPatternFlavor SPF2, Value *C);
Instruction *visitSelectInst(SelectInst &SI);
Instruction *visitSelectInstWithICmp(SelectInst &SI, ICmpInst *ICI);
Instruction *visitCallInst(CallInst &CI);
@@ -649,6 +661,57 @@
return 0;
}
+/// MatchSelectPattern - Pattern match integer [SU]MIN, [SU]MAX, and ABS idioms,
+/// returning the kind and providing the out parameter results if we
+/// successfully match.
+static SelectPatternFlavor
+MatchSelectPattern(Value *V, Value *&LHS, Value *&RHS) {
+ SelectInst *SI = dyn_cast<SelectInst>(V);
+ if (SI == 0) return SPF_UNKNOWN;
+
+ ICmpInst *ICI = dyn_cast<ICmpInst>(SI->getCondition());
+ if (ICI == 0) return SPF_UNKNOWN;
+
+ LHS = ICI->getOperand(0);
+ RHS = ICI->getOperand(1);
+
+ // (icmp X, Y) ? X : Y
+ if (SI->getTrueValue() == ICI->getOperand(0) &&
+ SI->getFalseValue() == ICI->getOperand(1)) {
+ switch (ICI->getPredicate()) {
+ default: return SPF_UNKNOWN; // Equality.
+ case ICmpInst::ICMP_UGT:
+ case ICmpInst::ICMP_UGE: return SPF_UMAX;
+ case ICmpInst::ICMP_SGT:
+ case ICmpInst::ICMP_SGE: return SPF_SMAX;
+ case ICmpInst::ICMP_ULT:
+ case ICmpInst::ICMP_ULE: return SPF_UMIN;
+ case ICmpInst::ICMP_SLT:
+ case ICmpInst::ICMP_SLE: return SPF_SMIN;
+ }
+ }
+
+ // (icmp X, Y) ? Y : X
+ if (SI->getTrueValue() == ICI->getOperand(1) &&
+ SI->getFalseValue() == ICI->getOperand(0)) {
+ switch (ICI->getPredicate()) {
+ default: return SPF_UNKNOWN; // Equality.
+ case ICmpInst::ICMP_UGT:
+ case ICmpInst::ICMP_UGE: return SPF_UMIN;
+ case ICmpInst::ICMP_SGT:
+ case ICmpInst::ICMP_SGE: return SPF_SMIN;
+ case ICmpInst::ICMP_ULT:
+ case ICmpInst::ICMP_ULE: return SPF_UMAX;
+ case ICmpInst::ICMP_SLT:
+ case ICmpInst::ICMP_SLE: return SPF_SMAX;
+ }
+ }
+
+ // TODO: (X > 4) ? X : 5 --> (X >= 5) ? X : 5 --> MAX(X, 5)
+
+ return SPF_UNKNOWN;
+}
+
/// isFreeToInvert - Return true if the specified value is free to invert (apply
/// ~ to). This happens in cases where the ~ can be eliminated.
static inline bool isFreeToInvert(Value *V) {
@@ -733,12 +796,12 @@
APInt MulExt = LHSExt * RHSExt;
- if (sign) {
- APInt Min = APInt::getSignedMinValue(W).sext(W * 2);
- APInt Max = APInt::getSignedMaxValue(W).sext(W * 2);
- return MulExt.slt(Min) || MulExt.sgt(Max);
- } else
+ if (!sign)
return MulExt.ugt(APInt::getLowBitsSet(W * 2, W));
+
+ APInt Min = APInt::getSignedMinValue(W).sext(W * 2);
+ APInt Max = APInt::getSignedMaxValue(W).sext(W * 2);
+ return MulExt.slt(Min) || MulExt.sgt(Max);
}
@@ -9479,9 +9542,6 @@
return ReplaceInstUsesWith(SI, TrueVal);
/// NOTE: if we wanted to, this is where to detect integer MIN/MAX
}
-
- /// NOTE: if we wanted to, this is where to detect integer ABS
-
return Changed ? &SI : 0;
}
@@ -9523,6 +9583,35 @@
return false;
}
+/// FoldSPFofSPF - We have an SPF (e.g. a min or max) of an SPF of the form:
+/// SPF2(SPF1(A, B), C)
+Instruction *InstCombiner::FoldSPFofSPF(Instruction *Inner,
+ SelectPatternFlavor SPF1,
+ Value *A, Value *B,
+ Instruction &Outer,
+ SelectPatternFlavor SPF2, Value *C) {
+ if (C == A || C == B) {
+ // MAX(MAX(A, B), B) -> MAX(A, B)
+ // MIN(MIN(a, b), a) -> MIN(a, b)
+ if (SPF1 == SPF2)
+ return ReplaceInstUsesWith(Outer, Inner);
+
+ // MAX(MIN(a, b), a) -> a
+ // MIN(MAX(a, b), a) -> a
+ if (SPF1 == SPF_SMIN && SPF2 == SPF_SMAX ||
+ SPF1 == SPF_SMAX && SPF2 == SPF_SMIN ||
+ SPF1 == SPF_UMIN && SPF2 == SPF_UMAX ||
+ SPF1 == SPF_UMAX && SPF2 == SPF_UMIN)
+ return ReplaceInstUsesWith(Outer, C);
+ }
+
+ // TODO: MIN(MIN(A, 23), 97)
+ return 0;
+}
+
+
+
+
Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
Value *CondVal = SI.getCondition();
Value *TrueVal = SI.getTrueValue();
@@ -9729,9 +9818,28 @@
// See if we can fold the select into one of our operands.
if (SI.getType()->isInteger()) {
- Instruction *FoldI = FoldSelectIntoOp(SI, TrueVal, FalseVal);
- if (FoldI)
+ if (Instruction *FoldI = FoldSelectIntoOp(SI, TrueVal, FalseVal))
return FoldI;
+
+ // MAX(MAX(a, b), a) -> MAX(a, b)
+ // MIN(MIN(a, b), a) -> MIN(a, b)
+ // MAX(MIN(a, b), a) -> a
+ // MIN(MAX(a, b), a) -> a
+ Value *LHS, *RHS, *LHS2, *RHS2;
+ if (SelectPatternFlavor SPF = MatchSelectPattern(&SI, LHS, RHS)) {
+ if (SelectPatternFlavor SPF2 = MatchSelectPattern(LHS, LHS2, RHS2))
+ if (Instruction *R = FoldSPFofSPF(cast<Instruction>(LHS),SPF2,LHS2,RHS2,
+ SI, SPF, RHS))
+ return R;
+ if (SelectPatternFlavor SPF2 = MatchSelectPattern(RHS, LHS2, RHS2))
+ if (Instruction *R = FoldSPFofSPF(cast<Instruction>(RHS),SPF2,LHS2,RHS2,
+ SI, SPF, LHS))
+ return R;
+ }
+
+ // TODO.
+ // ABS(-X) -> ABS(X)
+ // ABS(ABS(X)) -> ABS(X)
}
// See if we can fold the select into a phi node if the condition is a select.
Modified: llvm/trunk/test/Transforms/InstCombine/select.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/select.ll?rev=91814&r1=91813&r2=91814&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/select.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/select.ll Mon Dec 21 00:03:05 2009
@@ -382,3 +382,43 @@
; CHECK-NEXT: ret i32 %a
}
+
+define i32 @test30(i32 %x, i32 %y) {
+ %cmp = icmp sgt i32 %x, %y
+ %cond = select i1 %cmp, i32 %x, i32 %y
+ %cmp5 = icmp sgt i32 %cond, %x
+ %retval = select i1 %cmp5, i32 %cond, i32 %x
+ ret i32 %retval
+}
+
+define i32 @test31(i32 %x, i32 %y) {
+ %cmp = icmp ugt i32 %x, %y
+ %cond = select i1 %cmp, i32 %x, i32 %y
+ %cmp5 = icmp ugt i32 %cond, %x
+ %retval = select i1 %cmp5, i32 %cond, i32 %x
+ ret i32 %retval
+}
+
+define i32 @test32(i32 %x, i32 %y) {
+ %cmp = icmp sgt i32 %x, %y
+ %cond = select i1 %cmp, i32 %y, i32 %x
+ %cmp5 = icmp sgt i32 %cond, %x
+ %retval = select i1 %cmp5, i32 %x, i32 %cond
+ ret i32 %retval
+}
+
+define i32 @test33(i32 %x, i32 %y) {
+ %cmp = icmp sgt i32 %x, %y
+ %cond = select i1 %cmp, i32 %y, i32 %x
+ %cmp5 = icmp sgt i32 %cond, %x
+ %retval = select i1 %cmp5, i32 %cond, i32 %x
+ ret i32 %retval
+}
+
+define i32 @test34(i32 %x, i32 %y) {
+ %cmp = icmp sgt i32 %x, %y
+ %cond = select i1 %cmp, i32 %x, i32 %y
+ %cmp5 = icmp sgt i32 %cond, %x
+ %retval = select i1 %cmp5, i32 %x, i32 %cond
+ ret i32 %retval
+}
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