From 261075590b2bde348922b402bf982c33fb6475a8 Mon Sep 17 00:00:00 2001
From: Matt Arsenault <Matthew.Arsenault@amd.com>
Date: Thu, 9 Jun 2022 11:07:31 -0400
Subject: [PATCH] llvm-reduce: Handle reducing FP values to nan

Prefer 0/1 over NaN, but it may make more sense to invert this as FP
operations with nan inputs can universally be folded into something
else.
---
 llvm/test/tools/llvm-reduce/remove-operands-fp.ll | 19 ++++++++++++++++-
 llvm/tools/llvm-reduce/DeltaManager.cpp           |  1 +
 llvm/tools/llvm-reduce/deltas/ReduceOperands.cpp  | 26 +++++++++++++++++++++++
 llvm/tools/llvm-reduce/deltas/ReduceOperands.h    |  1 +
 4 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/llvm/test/tools/llvm-reduce/remove-operands-fp.ll b/llvm/test/tools/llvm-reduce/remove-operands-fp.ll
index 3e42ba5..e3ea033 100644
--- a/llvm/test/tools/llvm-reduce/remove-operands-fp.ll
+++ b/llvm/test/tools/llvm-reduce/remove-operands-fp.ll
@@ -6,7 +6,10 @@
 ; RUN: llvm-reduce --abort-on-invalid-reduction --delta-passes=operands-zero --test FileCheck --test-arg --check-prefixes=CHECK-INTERESTINGNESS --test-arg %s --test-arg --input-file %s -o %t
 ; RUN: FileCheck --check-prefixes=CHECK,ZERO %s < %t
 
-; RUN: llvm-reduce --test FileCheck --test-arg --check-prefixes=CHECK-INTERESTINGNESS --test-arg %s --test-arg --input-file %s -o %t
+; RUN: llvm-reduce --abort-on-invalid-reduction --delta-passes=operands-nan --test FileCheck --test-arg --check-prefixes=CHECK-INTERESTINGNESS --test-arg %s --test-arg --input-file %s -o %t
+; RUN: FileCheck --check-prefixes=CHECK,NAN %s < %t
+
+; RUN: llvm-reduce --abort-on-invalid-reduction --test FileCheck --test-arg --check-prefixes=CHECK-INTERESTINGNESS --test-arg %s --test-arg --input-file %s -o %t
 ; RUN: FileCheck --check-prefixes=CHECK,ZERO %s < %t
 
 ; CHECK-INTERESTINGNESS: = fadd float %
@@ -53,6 +56,20 @@
 ; ZERO: %fadd10 = fadd <2 x float> zeroinitializer, zeroinitializer
 ; ZERO: %fadd11 = fadd <2 x float> zeroinitializer, zeroinitializer
 
+
+; NAN: %fadd0 = fadd float %arg0, 0x7FF8000000000000
+; NAN: %fadd1 = fadd float 0x7FF8000000000000, 0x7FF8000000000000
+; NAN: %fadd2 = fadd float 0x7FF8000000000000, 0.000000e+00
+; NAN: %fadd3 = fadd float 0x7FF8000000000000, 1.000000e+00
+; NAN: %fadd4 = fadd float 0x7FF8000000000000, 0x7FF8000000000000
+; NAN: %fadd5 = fadd float 0x7FF8000000000000, 0x7FF8000000000000
+; NAN: %fadd6 = fadd <2 x float> %arg2, <float 0x7FF8000000000000, float 0x7FF8000000000000>
+; NAN: %fadd7 = fadd <2 x float> <float 0x7FF8000000000000, float 0x7FF8000000000000>, <float 0x7FF8000000000000, float 0x7FF8000000000000>
+; NAN: %fadd8 = fadd <2 x float> <float 0x7FF8000000000000, float 0x7FF8000000000000>, zeroinitializer
+; NAN: %fadd9 = fadd <2 x float> <float 0x7FF8000000000000, float 0x7FF8000000000000>, <float 1.000000e+00, float 1.000000e+00>
+; NAN: %fadd10 = fadd <2 x float> <float 0x7FF8000000000000, float 0x7FF8000000000000>, <float 0x7FF8000000000000, float 0x7FF8000000000000>
+; NAN: %fadd11 = fadd <2 x float> <float 0x7FF8000000000000, float 0x7FF8000000000000>, <float 0x7FF8000000000000, float 0x7FF8000000000000>
+
 define void @foo(float %arg0, float %arg1, <2 x float> %arg2, <2 x float> %arg3) {
 bb0:
   %fadd0 = fadd float %arg0, %arg1
diff --git a/llvm/tools/llvm-reduce/DeltaManager.cpp b/llvm/tools/llvm-reduce/DeltaManager.cpp
index 7a86997..49dd8f1 100644
--- a/llvm/tools/llvm-reduce/DeltaManager.cpp
+++ b/llvm/tools/llvm-reduce/DeltaManager.cpp
@@ -66,6 +66,7 @@ static cl::opt<std::string>
   DELTA_PASS("simplify-instructions", simplifyInstructionsDeltaPass)           \
   DELTA_PASS("operands-zero", reduceOperandsZeroDeltaPass)                     \
   DELTA_PASS("operands-one", reduceOperandsOneDeltaPass)                       \
+  DELTA_PASS("operands-nan", reduceOperandsNaNDeltaPass)                       \
   DELTA_PASS("operands-to-args", reduceOperandsToArgsDeltaPass)                \
   DELTA_PASS("operands-skip", reduceOperandsSkipDeltaPass)                     \
   DELTA_PASS("operand-bundles", reduceOperandBundesDeltaPass)                  \
diff --git a/llvm/tools/llvm-reduce/deltas/ReduceOperands.cpp b/llvm/tools/llvm-reduce/deltas/ReduceOperands.cpp
index 9c713f5..d008a39 100644
--- a/llvm/tools/llvm-reduce/deltas/ReduceOperands.cpp
+++ b/llvm/tools/llvm-reduce/deltas/ReduceOperands.cpp
@@ -105,3 +105,29 @@ void llvm::reduceOperandsZeroDeltaPass(TestRunner &Test) {
     extractOperandsFromModule(O, Program, ReduceValue);
   });
 }
+
+void llvm::reduceOperandsNaNDeltaPass(TestRunner &Test) {
+  errs() << "*** Reducing Operands to NaN...\n";
+  auto ReduceValue = [](Use &Op) -> Value * {
+    Type *Ty = Op->getType();
+    if (!Ty->isFPOrFPVectorTy())
+      return nullptr;
+
+    // Prefer 0.0 or 1.0 over NaN.
+    //
+    // TODO: Preferring NaN may make more sense because FP operations are more
+    // universally foldable.
+    if (match(Op.get(), m_NaN()) || isZeroOrOneFP(Op.get()))
+      return nullptr;
+
+    if (VectorType *VT = dyn_cast<VectorType>(Ty)) {
+      return ConstantVector::getSplat(VT->getElementCount(),
+                                      ConstantFP::getQNaN(VT->getElementType()));
+    }
+
+    return ConstantFP::getQNaN(Ty);
+  };
+  runDeltaPass(Test, [ReduceValue](Oracle &O, Module &Program) {
+    extractOperandsFromModule(O, Program, ReduceValue);
+  });
+}
diff --git a/llvm/tools/llvm-reduce/deltas/ReduceOperands.h b/llvm/tools/llvm-reduce/deltas/ReduceOperands.h
index 9fc3728c..034f49b 100644
--- a/llvm/tools/llvm-reduce/deltas/ReduceOperands.h
+++ b/llvm/tools/llvm-reduce/deltas/ReduceOperands.h
@@ -14,6 +14,7 @@
 namespace llvm {
 void reduceOperandsOneDeltaPass(TestRunner &Test);
 void reduceOperandsZeroDeltaPass(TestRunner &Test);
+void reduceOperandsNaNDeltaPass(TestRunner &Test);
 } // namespace llvm
 
 #endif
-- 
2.7.4