[GISel] KnownFPClass ValueTracking fix handling of vectors #143372

tgymnich · 2025-06-09T11:55:41Z

fix handling of vectors
abort analysis on physical registers
add some more tests

llvmbot · 2025-06-09T11:56:55Z

@llvm/pr-subscribers-llvm-globalisel

Author: Tim Gymnich (tgymnich)

Changes

fix handling of vectors
abort analysis on physical registers
add some more tests

Full diff: https://github.com/llvm/llvm-project/pull/143372.diff

2 Files Affected:

(modified) llvm/lib/CodeGen/GlobalISel/GISelValueTracking.cpp (+24-18)
(modified) llvm/unittests/CodeGen/GlobalISel/KnownFPClassTest.cpp (+98)

diff --git a/llvm/lib/CodeGen/GlobalISel/GISelValueTracking.cpp b/llvm/lib/CodeGen/GlobalISel/GISelValueTracking.cpp
index 6650ad25bed04..10d6a3af78720 100644
--- a/llvm/lib/CodeGen/GlobalISel/GISelValueTracking.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/GISelValueTracking.cpp
@@ -715,6 +715,9 @@ static bool outputDenormalIsIEEEOrPosZero(const MachineFunction &MF, LLT Ty) {
 void GISelValueTracking::computeKnownFPClass(Register R, KnownFPClass &Known,
                                              FPClassTest InterestedClasses,
                                              unsigned Depth) {
+  if (!R.isVirtual())
+    return;
+  
   LLT Ty = MRI.getType(R);
   APInt DemandedElts =
       Ty.isFixedVector() ? APInt::getAllOnes(Ty.getNumElements()) : APInt(1, 1);
@@ -758,6 +761,9 @@ void GISelValueTracking::computeKnownFPClass(Register R,
 
   assert(Depth <= MaxAnalysisRecursionDepth && "Limit Search Depth");
 
+  if (!R.isVirtual())
+    return;
+
   MachineInstr &MI = *MRI.getVRegDef(R);
   unsigned Opcode = MI.getOpcode();
   LLT DstTy = MRI.getType(R);
@@ -1046,7 +1052,7 @@ void GISelValueTracking::computeKnownFPClass(Register R,
     //
     if ((Known.KnownFPClasses & fcZero) != fcNone &&
         !Known.isKnownNeverSubnormal()) {
-      DenormalMode Mode = MF->getDenormalMode(getFltSemanticForLLT(DstTy));
+      DenormalMode Mode = MF->getDenormalMode(getFltSemanticForLLT(DstTy.getScalarType()));
       if (Mode != DenormalMode::getIEEE())
         Known.KnownFPClasses |= fcZero;
     }
@@ -1108,8 +1114,8 @@ void GISelValueTracking::computeKnownFPClass(Register R,
 
     // If the parent function flushes denormals, the canonical output cannot
     // be a denormal.
-    LLT Ty = MRI.getType(Val);
-    const fltSemantics &FPType = getFltSemanticForLLT(Ty.getScalarType());
+    LLT Ty = MRI.getType(Val).getScalarType();
+    const fltSemantics &FPType = getFltSemanticForLLT(Ty);
     DenormalMode DenormMode = MF->getDenormalMode(FPType);
     if (DenormMode == DenormalMode::getIEEE()) {
       if (KnownSrc.isKnownNever(fcPosZero))
@@ -1219,8 +1225,8 @@ void GISelValueTracking::computeKnownFPClass(Register R,
     if (KnownSrc.isKnownNeverNaN() && KnownSrc.cannotBeOrderedLessThanZero())
       Known.knownNot(fcNan);
 
-    LLT Ty = MRI.getType(Val);
-    const fltSemantics &FltSem = getFltSemanticForLLT(Ty.getScalarType());
+    LLT Ty = MRI.getType(Val).getScalarType();
+    const fltSemantics &FltSem = getFltSemanticForLLT(Ty);
     DenormalMode Mode = MF->getDenormalMode(FltSem);
 
     if (KnownSrc.isKnownNeverLogicalZero(Mode))
@@ -1339,18 +1345,18 @@ void GISelValueTracking::computeKnownFPClass(Register R,
 
         // (fadd x, 0.0) is guaranteed to return +0.0, not -0.0.
         if ((KnownLHS.isKnownNeverLogicalNegZero(
-                 MF->getDenormalMode(getFltSemanticForLLT(DstTy))) ||
+                 MF->getDenormalMode(getFltSemanticForLLT(DstTy.getScalarType()))) ||
              KnownRHS.isKnownNeverLogicalNegZero(
-                 MF->getDenormalMode(getFltSemanticForLLT(DstTy)))) &&
+                 MF->getDenormalMode(getFltSemanticForLLT(DstTy.getScalarType())))) &&
             // Make sure output negative denormal can't flush to -0
             outputDenormalIsIEEEOrPosZero(*MF, DstTy))
           Known.knownNot(fcNegZero);
       } else {
         // Only fsub -0, +0 can return -0
         if ((KnownLHS.isKnownNeverLogicalNegZero(
-                 MF->getDenormalMode(getFltSemanticForLLT(DstTy))) ||
+                 MF->getDenormalMode(getFltSemanticForLLT(DstTy.getScalarType()))) ||
              KnownRHS.isKnownNeverLogicalPosZero(
-                 MF->getDenormalMode(getFltSemanticForLLT(DstTy)))) &&
+                 MF->getDenormalMode(getFltSemanticForLLT(DstTy.getScalarType())))) &&
             // Make sure output negative denormal can't flush to -0
             outputDenormalIsIEEEOrPosZero(*MF, DstTy))
           Known.knownNot(fcNegZero);
@@ -1397,10 +1403,10 @@ void GISelValueTracking::computeKnownFPClass(Register R,
 
     if ((KnownRHS.isKnownNeverInfinity() ||
          KnownLHS.isKnownNeverLogicalZero(
-             MF->getDenormalMode(getFltSemanticForLLT(DstTy)))) &&
+             MF->getDenormalMode(getFltSemanticForLLT(DstTy.getScalarType())))) &&
         (KnownLHS.isKnownNeverInfinity() ||
          KnownRHS.isKnownNeverLogicalZero(
-             MF->getDenormalMode(getFltSemanticForLLT(DstTy)))))
+             MF->getDenormalMode(getFltSemanticForLLT(DstTy.getScalarType())))))
       Known.knownNot(fcNan);
 
     break;
@@ -1453,9 +1459,9 @@ void GISelValueTracking::computeKnownFPClass(Register R,
           (KnownLHS.isKnownNeverInfinity() ||
            KnownRHS.isKnownNeverInfinity()) &&
           ((KnownLHS.isKnownNeverLogicalZero(
-               MF->getDenormalMode(getFltSemanticForLLT(DstTy)))) ||
+               MF->getDenormalMode(getFltSemanticForLLT(DstTy.getScalarType())))) ||
            (KnownRHS.isKnownNeverLogicalZero(
-               MF->getDenormalMode(getFltSemanticForLLT(DstTy)))))) {
+               MF->getDenormalMode(getFltSemanticForLLT(DstTy.getScalarType())))))) {
         Known.knownNot(fcNan);
       }
 
@@ -1469,7 +1475,7 @@ void GISelValueTracking::computeKnownFPClass(Register R,
       if (KnownLHS.isKnownNeverNaN() && KnownRHS.isKnownNeverNaN() &&
           KnownLHS.isKnownNeverInfinity() &&
           KnownRHS.isKnownNeverLogicalZero(
-              MF->getDenormalMode(getFltSemanticForLLT(DstTy)))) {
+              MF->getDenormalMode(getFltSemanticForLLT(DstTy.getScalarType())))) {
         Known.knownNot(fcNan);
       }
 
@@ -1494,10 +1500,10 @@ void GISelValueTracking::computeKnownFPClass(Register R,
     // Infinity, nan and zero propagate from source.
     computeKnownFPClass(R, DemandedElts, InterestedClasses, Known, Depth + 1);
 
-    LLT DstTy = MRI.getType(Dst);
-    const fltSemantics &DstSem = getFltSemanticForLLT(DstTy.getScalarType());
-    LLT SrcTy = MRI.getType(Src);
-    const fltSemantics &SrcSem = getFltSemanticForLLT(SrcTy.getScalarType());
+    LLT DstTy = MRI.getType(Dst).getScalarType();
+    const fltSemantics &DstSem = getFltSemanticForLLT(DstTy);
+    LLT SrcTy = MRI.getType(Src).getScalarType();
+    const fltSemantics &SrcSem = getFltSemanticForLLT(SrcTy);
 
     // All subnormal inputs should be in the normal range in the result type.
     if (APFloat::isRepresentableAsNormalIn(SrcSem, DstSem)) {
diff --git a/llvm/unittests/CodeGen/GlobalISel/KnownFPClassTest.cpp b/llvm/unittests/CodeGen/GlobalISel/KnownFPClassTest.cpp
index 6ee571804e69f..040f0cfc92076 100644
--- a/llvm/unittests/CodeGen/GlobalISel/KnownFPClassTest.cpp
+++ b/llvm/unittests/CodeGen/GlobalISel/KnownFPClassTest.cpp
@@ -96,6 +96,104 @@ TEST_F(AArch64GISelMITest, TestFPClassCstVecNegZero) {
   EXPECT_EQ(true, Known.SignBit);
 }
 
+TEST_F(AArch64GISelMITest, TestFPClassCstZeroFPExt) {
+  StringRef MIRString = R"(
+   %c0:_(s32) = G_FCONSTANT float 0.0
+   %ext:_(s64) = nnan ninf G_FPEXT %c0
+   %copy_vector:_(s64) = COPY %ext
+)";
+
+  setUp(MIRString);
+  if (!TM)
+    GTEST_SKIP();
+
+  Register CopyReg = Copies[Copies.size() - 1];
+  MachineInstr *FinalCopy = MRI->getVRegDef(CopyReg);
+  Register SrcReg = FinalCopy->getOperand(1).getReg();
+
+  GISelValueTracking Info(*MF);
+
+  KnownFPClass Known = Info.computeKnownFPClass(SrcReg);
+
+  EXPECT_EQ(fcZero | fcNormal, Known.KnownFPClasses);
+  EXPECT_EQ(std::nullopt, Known.SignBit);
+}
+
+TEST_F(AArch64GISelMITest, TestFPClassCstVecZeroFPExt) {
+  StringRef MIRString = R"(
+   %c0:_(s32) = G_FCONSTANT float 0.0
+   %c1:_(s32) = G_FCONSTANT float 0.0
+   %c2:_(s32) = G_FCONSTANT float 0.0
+   %vector:_(<3 x s32>) = G_BUILD_VECTOR %c0, %c1, %c2
+   %ext:_(<3 x s64>) = nnan ninf G_FPEXT %vector
+   %copy_vector:_(<3 x s64>) = COPY %ext
+)";
+
+  setUp(MIRString);
+  if (!TM)
+    GTEST_SKIP();
+
+  Register CopyReg = Copies[Copies.size() - 1];
+  MachineInstr *FinalCopy = MRI->getVRegDef(CopyReg);
+  Register SrcReg = FinalCopy->getOperand(1).getReg();
+
+  GISelValueTracking Info(*MF);
+
+  KnownFPClass Known = Info.computeKnownFPClass(SrcReg);
+
+  EXPECT_EQ(fcZero | fcNormal, Known.KnownFPClasses);
+  EXPECT_EQ(std::nullopt, Known.SignBit);
+}
+
+TEST_F(AArch64GISelMITest, TestFPClassCstZeroFPTrunc) {
+  StringRef MIRString = R"(
+   %c0:_(s64) = G_FCONSTANT double 0.0
+   %trunc:_(s32) = nnan ninf G_FPTRUNC %c0
+   %copy_vector:_(s32) = COPY %trunc
+)";
+
+  setUp(MIRString);
+  if (!TM)
+    GTEST_SKIP();
+
+  Register CopyReg = Copies[Copies.size() - 1];
+  MachineInstr *FinalCopy = MRI->getVRegDef(CopyReg);
+  Register SrcReg = FinalCopy->getOperand(1).getReg();
+
+  GISelValueTracking Info(*MF);
+
+  KnownFPClass Known = Info.computeKnownFPClass(SrcReg);
+
+  EXPECT_EQ(fcZero | fcPosSubnormal | fcPosNormal, Known.KnownFPClasses);
+  EXPECT_EQ(false, Known.SignBit);
+}
+
+TEST_F(AArch64GISelMITest, TestFPClassCstVecZeroFPTrunc) {
+  StringRef MIRString = R"(
+   %c0:_(s64) = G_FCONSTANT double 0.0
+   %c1:_(s64) = G_FCONSTANT double 0.0
+   %c2:_(s64) = G_FCONSTANT double 0.0
+   %vector:_(<3 x s64>) = G_BUILD_VECTOR %c0, %c1, %c2
+   %trunc:_(<3 x s32>) = nnan ninf G_FPTRUNC %vector
+   %copy_vector:_(<3 x s32>) = COPY %trunc
+)";
+
+  setUp(MIRString);
+  if (!TM)
+    GTEST_SKIP();
+
+  Register CopyReg = Copies[Copies.size() - 1];
+  MachineInstr *FinalCopy = MRI->getVRegDef(CopyReg);
+  Register SrcReg = FinalCopy->getOperand(1).getReg();
+
+  GISelValueTracking Info(*MF);
+
+  KnownFPClass Known = Info.computeKnownFPClass(SrcReg);
+
+  EXPECT_EQ(fcZero | fcPosSubnormal | fcPosNormal, Known.KnownFPClasses);
+  EXPECT_EQ(false, Known.SignBit);
+}
+
 TEST_F(AArch64GISelMITest, TestFPClassSelectPos0) {
   StringRef MIRString = R"(
     %ptr:_(p0) = G_IMPLICIT_DEF

github-actions · 2025-06-09T11:58:03Z

✅ With the latest revision this PR passed the C/C++ code formatter.

llvm/lib/CodeGen/GlobalISel/GISelValueTracking.cpp

tgymnich · 2025-06-12T12:09:32Z

gentle ping @arsenm

tgymnich requested a review from arsenm June 9, 2025 11:56

tgymnich marked this pull request as ready for review June 9, 2025 11:56

llvmbot added the llvm:globalisel label Jun 9, 2025

arsenm reviewed Jun 9, 2025

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tgymnich requested a review from arsenm June 10, 2025 08:57

tgymnich added 3 commits June 12, 2025 12:11

guard against non-virtual registers

f7aa627

test fpext / fptrunc of scalars and vectors

a07f176

move register kind check to COPY

7c2c03d

tgymnich force-pushed the tim/fix-compute-known-fpclass branch from 950aef6 to 7c2c03d Compare June 12, 2025 12:11

arsenm approved these changes Jun 12, 2025

View reviewed changes

tgymnich merged commit 5aed480 into llvm:main Jun 12, 2025
5 of 7 checks passed

tomtor pushed a commit to tomtor/llvm-project that referenced this pull request Jun 14, 2025

[GISel] KnownFPClass ValueTracking fix handling of vectors (llvm#143372)

c3ea251

tgymnich deleted the tim/fix-compute-known-fpclass branch June 17, 2025 14:37

akuhlens pushed a commit to akuhlens/llvm-project that referenced this pull request Jun 24, 2025

[GISel] KnownFPClass ValueTracking fix handling of vectors (llvm#143372)

d4b1963

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