[llvm] 80f4bb5 - [GlobalISel] Extend G_SELECT of known condition combine to vectors.
Amara Emerson via llvm-commits
llvm-commits at lists.llvm.org
Thu Sep 30 12:17:02 PDT 2021
Author: Amara Emerson
Date: 2021-09-30T12:16:44-07:00
New Revision: 80f4bb5c61930c51b2eac6c5575198516483eff1
URL: https://github.com/llvm/llvm-project/commit/80f4bb5c61930c51b2eac6c5575198516483eff1
DIFF: https://github.com/llvm/llvm-project/commit/80f4bb5c61930c51b2eac6c5575198516483eff1.diff
LOG: [GlobalISel] Extend G_SELECT of known condition combine to vectors.
Adds a new utility function: isConstantOrConstantSplatVector().
Differential Revision: https://reviews.llvm.org/D110786
Added:
Modified:
llvm/include/llvm/CodeGen/GlobalISel/GenericMachineInstrs.h
llvm/include/llvm/CodeGen/GlobalISel/Utils.h
llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
llvm/lib/CodeGen/GlobalISel/Utils.cpp
llvm/test/CodeGen/AArch64/GlobalISel/combine-select.mir
Removed:
################################################################################
diff --git a/llvm/include/llvm/CodeGen/GlobalISel/GenericMachineInstrs.h b/llvm/include/llvm/CodeGen/GlobalISel/GenericMachineInstrs.h
index bb5f55789a0ec..65302e3549062 100644
--- a/llvm/include/llvm/CodeGen/GlobalISel/GenericMachineInstrs.h
+++ b/llvm/include/llvm/CodeGen/GlobalISel/GenericMachineInstrs.h
@@ -214,6 +214,18 @@ class GImplicitDef : public GenericMachineInstr {
}
};
+/// Represents a G_SELECT.
+class GSelect : public GenericMachineInstr {
+public:
+ Register getCondReg() const { return getReg(1); }
+ Register getTrueReg() const { return getReg(2); }
+ Register getFalseReg() const { return getReg(3); }
+
+ static bool classof(const MachineInstr *MI) {
+ return MI->getOpcode() == TargetOpcode::G_SELECT;
+ }
+};
+
} // namespace llvm
#endif // LLVM_CODEGEN_GLOBALISEL_GENERICMACHINEINSTRS_H
\ No newline at end of file
diff --git a/llvm/include/llvm/CodeGen/GlobalISel/Utils.h b/llvm/include/llvm/CodeGen/GlobalISel/Utils.h
index a6e6e4942d22d..39a5ee71c7102 100644
--- a/llvm/include/llvm/CodeGen/GlobalISel/Utils.h
+++ b/llvm/include/llvm/CodeGen/GlobalISel/Utils.h
@@ -397,6 +397,12 @@ bool isBuildVectorAllOnes(const MachineInstr &MI,
Optional<RegOrConstant> getVectorSplat(const MachineInstr &MI,
const MachineRegisterInfo &MRI);
+/// Determines if \p MI defines a constant integer or a splat vector of
+/// constant integers.
+/// \returns the scalar constant or None.
+Optional<APInt> isConstantOrConstantSplatVector(MachineInstr &MI,
+ const MachineRegisterInfo &MRI);
+
/// Attempt to match a unary predicate against a scalar/splat constant or every
/// element of a constant G_BUILD_VECTOR. If \p ConstVal is null, the source
/// value was undef.
diff --git a/llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp b/llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
index 0515e44c6c947..032b41010fa18 100644
--- a/llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
@@ -2239,13 +2239,13 @@ bool CombinerHelper::matchUndefSelectCmp(MachineInstr &MI) {
}
bool CombinerHelper::matchConstantSelectCmp(MachineInstr &MI, unsigned &OpIdx) {
- assert(MI.getOpcode() == TargetOpcode::G_SELECT);
- if (auto MaybeCstCmp =
- getIConstantVRegValWithLookThrough(MI.getOperand(1).getReg(), MRI)) {
- OpIdx = MaybeCstCmp->Value.isNullValue() ? 3 : 2;
- return true;
- }
- return false;
+ GSelect &SelMI = cast<GSelect>(MI);
+ auto Cst =
+ isConstantOrConstantSplatVector(*MRI.getVRegDef(SelMI.getCondReg()), MRI);
+ if (!Cst)
+ return false;
+ OpIdx = Cst->isZero() ? 3 : 2;
+ return true;
}
bool CombinerHelper::eraseInst(MachineInstr &MI) {
diff --git a/llvm/lib/CodeGen/GlobalISel/Utils.cpp b/llvm/lib/CodeGen/GlobalISel/Utils.cpp
index 3c09df0b69703..d878f14f27bf9 100644
--- a/llvm/lib/CodeGen/GlobalISel/Utils.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/Utils.cpp
@@ -1016,6 +1016,19 @@ Optional<RegOrConstant> llvm::getVectorSplat(const MachineInstr &MI,
return RegOrConstant(Reg);
}
+Optional<APInt>
+llvm::isConstantOrConstantSplatVector(MachineInstr &MI,
+ const MachineRegisterInfo &MRI) {
+ Register Def = MI.getOperand(0).getReg();
+ if (auto C = getIConstantVRegValWithLookThrough(Def, MRI))
+ return C->Value;
+ auto MaybeCst = getBuildVectorConstantSplat(MI, MRI);
+ if (!MaybeCst)
+ return None;
+ const unsigned ScalarSize = MRI.getType(Def).getScalarSizeInBits();
+ return APInt(ScalarSize, *MaybeCst, true);
+}
+
bool llvm::matchUnaryPredicate(
const MachineRegisterInfo &MRI, Register Reg,
std::function<bool(const Constant *ConstVal)> Match, bool AllowUndefs) {
diff --git a/llvm/test/CodeGen/AArch64/GlobalISel/combine-select.mir b/llvm/test/CodeGen/AArch64/GlobalISel/combine-select.mir
index 83e5abdd736dd..6f2e8121c4bcd 100644
--- a/llvm/test/CodeGen/AArch64/GlobalISel/combine-select.mir
+++ b/llvm/test/CodeGen/AArch64/GlobalISel/combine-select.mir
@@ -9,7 +9,7 @@ body: |
liveins: $x0, $x1
; CHECK-LABEL: name: test_combine_select_same_res
; CHECK: [[COPY:%[0-9]+]]:_(s64) = COPY $x0
- ; CHECK: $x0 = COPY [[COPY]](s64)
+ ; CHECK-NEXT: $x0 = COPY [[COPY]](s64)
%0:_(s64) = COPY $x0
%1:_(s1) = G_TRUNC %0
%2:_(s64) = G_SELECT %1, %0, %0
@@ -23,7 +23,7 @@ body: |
liveins: $x0, $x1
; CHECK-LABEL: name: test_combine_select_undef_res0_res1
; CHECK: [[COPY:%[0-9]+]]:_(s64) = COPY $x0
- ; CHECK: $x0 = COPY [[COPY]](s64)
+ ; CHECK-NEXT: $x0 = COPY [[COPY]](s64)
%0:_(s64) = COPY $x0
%1:_(s64) = COPY $x1
%2:_(s1) = G_IMPLICIT_DEF
@@ -38,7 +38,7 @@ body: |
liveins: $x0, $x1
; CHECK-LABEL: name: test_combine_select_false_res0_res1
; CHECK: [[COPY:%[0-9]+]]:_(s64) = COPY $x1
- ; CHECK: $x0 = COPY [[COPY]](s64)
+ ; CHECK-NEXT: $x0 = COPY [[COPY]](s64)
%0:_(s64) = COPY $x0
%1:_(s64) = COPY $x1
%2:_(s1) = G_CONSTANT i1 false
@@ -46,6 +46,22 @@ body: |
$x0 = COPY %3(s64)
...
---
+# vector select (false, x, y) -> y
+name: test_combine_vector_select_false_res0_res1
+body: |
+ bb.1:
+ liveins: $q0, $q1
+ ; CHECK-LABEL: name: test_combine_vector_select_false_res0_res1
+ ; CHECK: [[COPY:%[0-9]+]]:_(<4 x s32>) = COPY $q1
+ ; CHECK-NEXT: $q0 = COPY [[COPY]](<4 x s32>)
+ %0:_(<4 x s32>) = COPY $q0
+ %1:_(<4 x s32>) = COPY $q1
+ %2:_(s1) = G_CONSTANT i1 false
+ %condvec:_(<4 x s1>) = G_BUILD_VECTOR %2, %2, %2, %2
+ %3:_(<4 x s32>) = G_SELECT %condvec, %0, %1
+ $q0 = COPY %3(<4 x s32>)
+...
+---
# select (true, x, y) -> x
name: test_combine_select_true_res0_res1
body: |
@@ -53,10 +69,26 @@ body: |
liveins: $x0, $x1
; CHECK-LABEL: name: test_combine_select_true_res0_res1
; CHECK: [[COPY:%[0-9]+]]:_(s64) = COPY $x0
- ; CHECK: $x0 = COPY [[COPY]](s64)
+ ; CHECK-NEXT: $x0 = COPY [[COPY]](s64)
%0:_(s64) = COPY $x0
%1:_(s64) = COPY $x1
%2:_(s1) = G_CONSTANT i1 true
%3:_(s64) = G_SELECT %2, %0, %1
$x0 = COPY %3(s64)
...
+---
+# vector select (true, x, y) -> x
+name: test_combine_vector_select_true_res0_res1
+body: |
+ bb.1:
+ liveins: $q0, $q1
+ ; CHECK-LABEL: name: test_combine_vector_select_true_res0_res1
+ ; CHECK: [[COPY:%[0-9]+]]:_(<4 x s32>) = COPY $q0
+ ; CHECK-NEXT: $q0 = COPY [[COPY]](<4 x s32>)
+ %0:_(<4 x s32>) = COPY $q0
+ %1:_(<4 x s32>) = COPY $q1
+ %2:_(s1) = G_CONSTANT i1 true
+ %condvec:_(<4 x s1>) = G_BUILD_VECTOR %2, %2, %2, %2
+ %3:_(<4 x s32>) = G_SELECT %condvec, %0, %1
+ $q0 = COPY %3(<4 x s32>)
+...
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