Recognize nested MIN-MAX operations.
Rationale:
Prior to this CL, select optimizer and instruction
simplifier were unable to deal with more than one
select. This CLs improves MIN-MAX recognition by
allowing select diamonds to nest deeper and by
recognizing constant clipping operations. This
yields better optimizable code, as shown with
more saturation idioms.
Bug: b/74026074
Test: test-art-host,target
Change-Id: I8a616a19475f1ae87c2b5210afc76b14265bd571
diff --git a/compiler/optimizing/instruction_simplifier.cc b/compiler/optimizing/instruction_simplifier.cc
index 676fe6b..7d0add3 100644
--- a/compiler/optimizing/instruction_simplifier.cc
+++ b/compiler/optimizing/instruction_simplifier.cc
@@ -903,6 +903,30 @@
to_type == DataType::Type::kInt64);
}
+// Returns an acceptable substitution for "a" on the select
+// construct "a <cmp> b ? c : .." during MIN/MAX recognition.
+static HInstruction* AllowInMinMax(IfCondition cmp,
+ HInstruction* a,
+ HInstruction* b,
+ HInstruction* c) {
+ int64_t value = 0;
+ if (IsInt64AndGet(b, /*out*/ &value) &&
+ (((cmp == kCondLT || cmp == kCondLE) && c->IsMax()) ||
+ ((cmp == kCondGT || cmp == kCondGE) && c->IsMin()))) {
+ HConstant* other = c->AsBinaryOperation()->GetConstantRight();
+ if (other != nullptr && a == c->AsBinaryOperation()->GetLeastConstantLeft()) {
+ int64_t other_value = Int64FromConstant(other);
+ bool is_max = (cmp == kCondLT || cmp == kCondLE);
+ // Allow the max for a < 100 ? max(a, -100) : ..
+ // or the min for a > -100 ? min(a, 100) : ..
+ if (is_max ? (value >= other_value) : (value <= other_value)) {
+ return c;
+ }
+ }
+ }
+ return nullptr;
+}
+
void InstructionSimplifierVisitor::VisitSelect(HSelect* select) {
HInstruction* replace_with = nullptr;
HInstruction* condition = select->GetCondition();
@@ -946,9 +970,17 @@
DataType::Type t_type = true_value->GetType();
DataType::Type f_type = false_value->GetType();
// Here we have a <cmp> b ? true_value : false_value.
- // Test if both values are compatible integral types (resulting
- // MIN/MAX/ABS type will be int or long, like the condition).
+ // Test if both values are compatible integral types (resulting MIN/MAX/ABS
+ // type will be int or long, like the condition). Replacements are general,
+ // but assume conditions prefer constants on the right.
if (DataType::IsIntegralType(t_type) && DataType::Kind(t_type) == DataType::Kind(f_type)) {
+ // Allow a < 100 ? max(a, -100) : ..
+ // or a > -100 ? min(a, 100) : ..
+ // to use min/max instead of a to detect nested min/max expressions.
+ HInstruction* new_a = AllowInMinMax(cmp, a, b, true_value);
+ if (new_a != nullptr) {
+ a = new_a;
+ }
// Try to replace typical integral MIN/MAX/ABS constructs.
if ((cmp == kCondLT || cmp == kCondLE || cmp == kCondGT || cmp == kCondGE) &&
((a == true_value && b == false_value) ||
@@ -957,19 +989,16 @@
// or a > b ? a : b (MAX) or a > b ? b : a (MIN).
bool is_min = (cmp == kCondLT || cmp == kCondLE) == (a == true_value);
replace_with = NewIntegralMinMax(GetGraph()->GetAllocator(), a, b, select, is_min);
- } else if (true_value->IsNeg()) {
- HInstruction* negated = true_value->InputAt(0);
- if ((cmp == kCondLT || cmp == kCondLE) &&
- (a == negated && a == false_value && IsInt64Value(b, 0))) {
- // Found a < 0 ? -a : a which can be replaced by ABS(a).
- replace_with = NewIntegralAbs(GetGraph()->GetAllocator(), false_value, select);
- }
- } else if (false_value->IsNeg()) {
- HInstruction* negated = false_value->InputAt(0);
- if ((cmp == kCondGT || cmp == kCondGE) &&
- (a == true_value && a == negated && IsInt64Value(b, 0))) {
- // Found a > 0 ? a : -a which can be replaced by ABS(a).
- replace_with = NewIntegralAbs(GetGraph()->GetAllocator(), true_value, select);
+ } else if (((cmp == kCondLT || cmp == kCondLE) && true_value->IsNeg()) ||
+ ((cmp == kCondGT || cmp == kCondGE) && false_value->IsNeg())) {
+ bool negLeft = (cmp == kCondLT || cmp == kCondLE);
+ HInstruction* the_negated = negLeft ? true_value->InputAt(0) : false_value->InputAt(0);
+ HInstruction* not_negated = negLeft ? false_value : true_value;
+ if (a == the_negated && a == not_negated && IsInt64Value(b, 0)) {
+ // Found a < 0 ? -a : a
+ // or a > 0 ? a : -a
+ // which can be replaced by ABS(a).
+ replace_with = NewIntegralAbs(GetGraph()->GetAllocator(), a, select);
}
} else if (true_value->IsSub() && false_value->IsSub()) {
HInstruction* true_sub1 = true_value->InputAt(0);
@@ -981,8 +1010,8 @@
((cmp == kCondLT || cmp == kCondLE) &&
(a == true_sub2 && b == true_sub1 && a == false_sub1 && b == false_sub2))) &&
AreLowerPrecisionArgs(t_type, a, b)) {
- // Found a > b ? a - b : b - a or
- // a < b ? b - a : a - b
+ // Found a > b ? a - b : b - a
+ // or a < b ? b - a : a - b
// which can be replaced by ABS(a - b) for lower precision operands a, b.
replace_with = NewIntegralAbs(GetGraph()->GetAllocator(), true_value, select);
}
diff --git a/compiler/optimizing/select_generator.cc b/compiler/optimizing/select_generator.cc
index 66e5142..3f52bdd 100644
--- a/compiler/optimizing/select_generator.cc
+++ b/compiler/optimizing/select_generator.cc
@@ -43,12 +43,16 @@
for (HInstructionIterator it(block->GetInstructions()); !it.Done(); it.Advance()) {
HInstruction* instruction = it.Current();
if (instruction->IsControlFlow()) {
- if (num_instructions > kMaxInstructionsInBranch) {
- return false;
- }
return instruction->IsGoto() || instruction->IsReturn();
} else if (instruction->CanBeMoved() && !instruction->HasSideEffects()) {
- num_instructions++;
+ if (instruction->IsSelect() &&
+ instruction->AsSelect()->GetCondition()->GetBlock() == block) {
+ // Count one HCondition and HSelect in the same block as a single instruction.
+ // This enables finding nested selects.
+ continue;
+ } else if (++num_instructions > kMaxInstructionsInBranch) {
+ return false; // bail as soon as we exceed number of allowed instructions
+ }
} else {
return false;
}
@@ -97,6 +101,7 @@
HBasicBlock* true_block = if_instruction->IfTrueSuccessor();
HBasicBlock* false_block = if_instruction->IfFalseSuccessor();
DCHECK_NE(true_block, false_block);
+
if (!IsSimpleBlock(true_block) ||
!IsSimpleBlock(false_block) ||
!BlocksMergeTogether(true_block, false_block)) {
@@ -107,10 +112,10 @@
// If the branches are not empty, move instructions in front of the If.
// TODO(dbrazdil): This puts an instruction between If and its condition.
// Implement moving of conditions to first users if possible.
- if (!true_block->IsSingleGoto() && !true_block->IsSingleReturn()) {
+ while (!true_block->IsSingleGoto() && !true_block->IsSingleReturn()) {
true_block->GetFirstInstruction()->MoveBefore(if_instruction);
}
- if (!false_block->IsSingleGoto() && !false_block->IsSingleReturn()) {
+ while (!false_block->IsSingleGoto() && !false_block->IsSingleReturn()) {
false_block->GetFirstInstruction()->MoveBefore(if_instruction);
}
DCHECK(true_block->IsSingleGoto() || true_block->IsSingleReturn());
diff --git a/test/678-checker-simd-saturation/src/Main.java b/test/678-checker-simd-saturation/src/Main.java
index decc691..7a22ca1 100644
--- a/test/678-checker-simd-saturation/src/Main.java
+++ b/test/678-checker-simd-saturation/src/Main.java
@@ -397,7 +397,22 @@
}
}
- // TODO: recognize the more common if-else too.
+ /// CHECK-START: void Main.satAlt2(short[], short[], short[]) loop_optimization (before)
+ /// CHECK-DAG: <<Clp1:i\d+>> IntConstant -32768 loop:none
+ /// CHECK-DAG: <<Clp2:i\d+>> IntConstant 32767 loop:none
+ /// CHECK-DAG: <<Get1:s\d+>> ArrayGet [{{l\d+}},<<Phi:i\d+>>] loop:<<Loop:B\d+>> outer_loop:none
+ /// CHECK-DAG: <<Get2:s\d+>> ArrayGet [{{l\d+}},<<Phi>>] loop:<<Loop>> outer_loop:none
+ /// CHECK-DAG: <<Add:i\d+>> Add [<<Get1>>,<<Get2>>] loop:<<Loop>> outer_loop:none
+ /// CHECK-DAG: <<Max:i\d+>> Max [<<Add>>,<<Clp1>>] loop:<<Loop>> outer_loop:none
+ /// CHECK-DAG: <<Min:i\d+>> Min [<<Max>>,<<Clp2>>] loop:<<Loop>> outer_loop:none
+ /// CHECK-DAG: <<Conv:s\d+>> TypeConversion [<<Min>>] loop:<<Loop>> outer_loop:none
+ /// CHECK-DAG: ArraySet [{{l\d+}},<<Phi>>,<<Conv>>] loop:<<Loop>> outer_loop:none
+ //
+ /// CHECK-START-{ARM,ARM64}: void Main.satAlt2(short[], short[], short[]) loop_optimization (after)
+ /// CHECK-DAG: <<Get1:d\d+>> VecLoad [{{l\d+}},<<Phi:i\d+>>] loop:<<Loop:B\d+>> outer_loop:none
+ /// CHECK-DAG: <<Get2:d\d+>> VecLoad [{{l\d+}},<<Phi>>] loop:<<Loop>> outer_loop:none
+ /// CHECK-DAG: <<Add:d\d+>> VecSaturationAdd [<<Get1>>,<<Get2>>] packed_type:Int16 loop:<<Loop>> outer_loop:none
+ /// CHECK-DAG: VecStore [{{l\d+}},<<Phi>>,<<Add>>] loop:<<Loop>> outer_loop:none
public static void satAlt2(short[] a, short[] b, short[] c) {
int n = Math.min(a.length, Math.min(b.length, c.length));
for (int i = 0; i < n; i++) {
@@ -411,7 +426,11 @@
}
}
- // TODO: recognize conditional too.
+ /// CHECK-START-{ARM,ARM64}: void Main.satAlt3(short[], short[], short[]) loop_optimization (after)
+ /// CHECK-DAG: <<Get1:d\d+>> VecLoad [{{l\d+}},<<Phi:i\d+>>] loop:<<Loop:B\d+>> outer_loop:none
+ /// CHECK-DAG: <<Get2:d\d+>> VecLoad [{{l\d+}},<<Phi>>] loop:<<Loop>> outer_loop:none
+ /// CHECK-DAG: <<Add:d\d+>> VecSaturationAdd [<<Get1>>,<<Get2>>] packed_type:Int16 loop:<<Loop>> outer_loop:none
+ /// CHECK-DAG: VecStore [{{l\d+}},<<Phi>>,<<Add>>] loop:<<Loop>> outer_loop:none
public static void satAlt3(short[] a, short[] b, short[] c) {
int n = Math.min(a.length, Math.min(b.length, c.length));
for (int i = 0; i < n; i++) {
diff --git a/test/679-checker-minmax/src/Main.java b/test/679-checker-minmax/src/Main.java
index 38085bb..4f0261c 100644
--- a/test/679-checker-minmax/src/Main.java
+++ b/test/679-checker-minmax/src/Main.java
@@ -19,6 +19,10 @@
*/
public class Main {
+ //
+ // Different types.
+ //
+
/// CHECK-START: int Main.min1(int, int) instruction_simplifier$after_inlining (before)
/// CHECK-DAG: <<Cnd:z\d+>> GreaterThanOrEqual [<<Op1:i\d+>>,<<Op2:i\d+>>]
/// CHECK-DAG: <<Sel:i\d+>> Select [<<Op1>>,<<Op2>>,<<Cnd>>]
@@ -229,7 +233,116 @@
return a >= b ? a : b;
}
+
+ //
+ // Complications.
+ //
+
+ // TODO: coming soon, under discussion
+ public static int min0(int[] a, int[] b) {
+ // Repeat of array references needs finding the common subexpressions
+ // prior to doing the select and min/max recognition.
+ return a[0] <= b[0] ? a[0] : b[0];
+ }
+
+ // TODO: coming soon, under discussion
+ public static int max0(int[] a, int[] b) {
+ // Repeat of array references needs finding the common subexpressions
+ // prior to doing the select and min/max recognition.
+ return a[0] >= b[0] ? a[0] : b[0];
+ }
+
+ /// CHECK-START: int Main.minmax1(int) instruction_simplifier$after_inlining (before)
+ /// CHECK-DAG: <<Par:i\d+>> ParameterValue
+ /// CHECK-DAG: <<P100:i\d+>> IntConstant 100
+ /// CHECK-DAG: <<M100:i\d+>> IntConstant -100
+ /// CHECK-DAG: <<Cnd1:z\d+>> LessThanOrEqual [<<Par>>,<<P100>>]
+ /// CHECK-DAG: <<Sel1:i\d+>> Select [<<P100>>,<<Par>>,<<Cnd1>>]
+ /// CHECK-DAG: <<Cnd2:z\d+>> GreaterThanOrEqual [<<Sel1>>,<<M100>>]
+ /// CHECK-DAG: <<Sel2:i\d+>> Select [<<M100>>,<<Sel1>>,<<Cnd2>>]
+ /// CHECK-DAG: Return [<<Sel2>>]
+ //
+ /// CHECK-START: int Main.minmax1(int) instruction_simplifier$after_inlining (after)
+ /// CHECK-DAG: <<Par:i\d+>> ParameterValue
+ /// CHECK-DAG: <<P100:i\d+>> IntConstant 100
+ /// CHECK-DAG: <<M100:i\d+>> IntConstant -100
+ /// CHECK-DAG: <<Min:i\d+>> Min [<<Par>>,<<P100>>]
+ /// CHECK-DAG: <<Max:i\d+>> Max [<<Min>>,<<M100>>]
+ /// CHECK-DAG: Return [<<Max>>]
+ //
+ /// CHECK-START: int Main.minmax1(int) instruction_simplifier$after_inlining (after)
+ /// CHECK-NOT: Select
+ public static int minmax1(int x) {
+ // Simple if-if gives clean select sequence.
+ if (x > 100) {
+ x = 100;
+ }
+ if (x < -100) {
+ x = -100;
+ }
+ return x;
+ }
+
+ /// CHECK-START: int Main.minmax2(int) instruction_simplifier$after_inlining (before)
+ /// CHECK-DAG: <<Par:i\d+>> ParameterValue
+ /// CHECK-DAG: <<P100:i\d+>> IntConstant 100
+ /// CHECK-DAG: <<M100:i\d+>> IntConstant -100
+ /// CHECK-DAG: <<Cnd1:z\d+>> LessThanOrEqual [<<Par>>,<<P100>>]
+ /// CHECK-DAG: <<Cnd2:z\d+>> GreaterThanOrEqual [<<Par>>,<<M100>>]
+ /// CHECK-DAG: <<Sel1:i\d+>> Select [<<M100>>,<<Par>>,<<Cnd2>>]
+ /// CHECK-DAG: <<Sel2:i\d+>> Select [<<P100>>,<<Sel1>>,<<Cnd1>>]
+ /// CHECK-DAG: Return [<<Sel2>>]
+ //
+ /// CHECK-START: int Main.minmax2(int) instruction_simplifier$after_inlining (after)
+ /// CHECK-DAG: <<Par:i\d+>> ParameterValue
+ /// CHECK-DAG: <<P100:i\d+>> IntConstant 100
+ /// CHECK-DAG: <<M100:i\d+>> IntConstant -100
+ /// CHECK-DAG: <<Max:i\d+>> Max [<<Par>>,<<M100>>]
+ /// CHECK-DAG: <<Min:i\d+>> Min [<<Max>>,<<P100>>]
+ /// CHECK-DAG: Return [<<Min>>]
+ //
+ /// CHECK-START: int Main.minmax2(int) instruction_simplifier$after_inlining (after)
+ /// CHECK-NOT: Select
+ public static int minmax2(int x) {
+ // Simple if-else requires inspecting bounds of resulting selects.
+ if (x > 100) {
+ x = 100;
+ } else if (x < -100) {
+ x = -100;
+ }
+ return x;
+ }
+
+ /// CHECK-START: int Main.minmax3(int) instruction_simplifier$after_inlining (after)
+ /// CHECK-DAG: <<Par:i\d+>> ParameterValue
+ /// CHECK-DAG: <<P100:i\d+>> IntConstant 100
+ /// CHECK-DAG: <<M100:i\d+>> IntConstant -100
+ /// CHECK-DAG: <<Max:i\d+>> Max [<<Par>>,<<M100>>]
+ /// CHECK-DAG: <<Min:i\d+>> Min [<<Max>>,<<P100>>]
+ /// CHECK-DAG: Return [<<Min>>]
+ //
+ /// CHECK-START: int Main.minmax3(int) instruction_simplifier$after_inlining (after)
+ /// CHECK-NOT: Select
+ public static int minmax3(int x) {
+ return (x > 100) ? 100 : ((x < -100) ? -100 : x);
+ }
+
+ /// CHECK-START: int Main.minmax4(int) instruction_simplifier$after_inlining (after)
+ /// CHECK-DAG: <<Par:i\d+>> ParameterValue
+ /// CHECK-DAG: <<P100:i\d+>> IntConstant 100
+ /// CHECK-DAG: <<M100:i\d+>> IntConstant -100
+ /// CHECK-DAG: <<Min:i\d+>> Min [<<Par>>,<<P100>>]
+ /// CHECK-DAG: <<Max:i\d+>> Max [<<Min>>,<<M100>>]
+ /// CHECK-DAG: Return [<<Max>>]
+ //
+ /// CHECK-START: int Main.minmax4(int) instruction_simplifier$after_inlining (after)
+ /// CHECK-NOT: Select
+ public static int minmax4(int x) {
+ return (x < -100) ? -100 : ((x > 100) ? 100 : x);
+ }
+
public static void main(String[] args) {
+ // Types.
expectEquals(10, min1(10, 20));
expectEquals(10, min2(10, 20));
expectEquals(10, min3(10, 20));
@@ -244,6 +357,23 @@
expectEquals(20, max5((short) 10, (short) 20));
expectEquals(20, max6((byte) 10, (byte) 20));
expectEquals(20L, max7(10L, 20L));
+ // Complications.
+ int[] a = { 10 };
+ int[] b = { 20 };
+ expectEquals(10, min0(a, b));
+ expectEquals(20, max0(a, b));
+ expectEquals(-100, minmax1(-200));
+ expectEquals(10, minmax1(10));
+ expectEquals(100, minmax1(200));
+ expectEquals(-100, minmax2(-200));
+ expectEquals(10, minmax2(10));
+ expectEquals(100, minmax2(200));
+ expectEquals(-100, minmax3(-200));
+ expectEquals(10, minmax3(10));
+ expectEquals(100, minmax3(200));
+ expectEquals(-100, minmax4(-200));
+ expectEquals(10, minmax4(10));
+ expectEquals(100, minmax4(200));
System.out.println("passed");
}
