[llvm] r343364 - [ValueTracking] Allow select patterns to work on FP vectors

[Thomas Lively via llvm-commits]

Author: tlively
Date: Fri Sep 28 14:36:43 2018
New Revision: 343364

URL: http://llvm.org/viewvc/llvm-project?rev=343364&view=rev
Log:
[ValueTracking] Allow select patterns to work on FP vectors

Summary:
This CL allows constant vectors of floats to be recognized as non-NaN
and non-zero in select patterns. This change makes
`matchSelectPattern` more powerful generally, but was motivated
specifically because I wanted fminnan and fmaxnan to be created for
vector versions of the scalar patterns they are created for.

Tested with check-all on all targets. A testcase in the WebAssembly
backend that tests the non-nan codepath is in an upcoming CL.

Reviewers: aheejin, dschuff

Subscribers: sunfish, llvm-commits

Differential Revision: https://reviews.llvm.org/D52324

Modified:
    llvm/trunk/lib/Analysis/ValueTracking.cpp
    llvm/trunk/unittests/Analysis/ValueTrackingTest.cpp

Modified: llvm/trunk/lib/Analysis/ValueTracking.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ValueTracking.cpp?rev=343364&r1=343363&r2=343364&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/ValueTracking.cpp (original)
+++ llvm/trunk/lib/Analysis/ValueTracking.cpp Fri Sep 28 14:36:43 2018
@@ -4397,12 +4397,34 @@ static bool isKnownNonNaN(const Value *V
 
   if (auto *C = dyn_cast<ConstantFP>(V))
     return !C->isNaN();
+
+  if (auto *C = dyn_cast<ConstantDataVector>(V)) {
+    if (!C->getElementType()->isFloatingPointTy())
+      return false;
+    for (unsigned I = 0, E = C->getNumElements(); I < E; ++I) {
+      if (C->getElementAsAPFloat(I).isNaN())
+        return false;
+    }
+    return true;
+  }
+
   return false;
 }
 
 static bool isKnownNonZero(const Value *V) {
   if (auto *C = dyn_cast<ConstantFP>(V))
     return !C->isZero();
+
+  if (auto *C = dyn_cast<ConstantDataVector>(V)) {
+    if (!C->getElementType()->isFloatingPointTy())
+      return false;
+    for (unsigned I = 0, E = C->getNumElements(); I < E; ++I) {
+      if (C->getElementAsAPFloat(I).isZero())
+        return false;
+    }
+    return true;
+  }
+
   return false;
 }
 

Modified: llvm/trunk/unittests/Analysis/ValueTrackingTest.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/Analysis/ValueTrackingTest.cpp?rev=343364&r1=343363&r2=343364&view=diff
==============================================================================
--- llvm/trunk/unittests/Analysis/ValueTrackingTest.cpp (original)
+++ llvm/trunk/unittests/Analysis/ValueTrackingTest.cpp Fri Sep 28 14:36:43 2018
@@ -149,6 +149,64 @@ TEST_F(MatchSelectPatternTest, FMinConst
   expectPattern({SPF_FMINNUM, SPNB_RETURNS_OTHER, true});
 }
 
+TEST_F(MatchSelectPatternTest, VectorFMinNaN) {
+  parseAssembly(
+      "define <4 x float> @test(<4 x float> %a) {\n"
+      "  %1 = fcmp ule <4 x float> %a, \n"
+      "    <float 5.0, float 5.0, float 5.0, float 5.0>\n"
+      "  %A = select <4 x i1> %1, <4 x float> %a,\n"
+      "     <4 x float> <float 5.0, float 5.0, float 5.0, float 5.0>\n"
+      "  ret <4 x float> %A\n"
+      "}\n");
+  // Check that pattern matching works on vectors where each lane has the same
+  // unordered pattern.
+  expectPattern({SPF_FMINNUM, SPNB_RETURNS_NAN, false});
+}
+
+TEST_F(MatchSelectPatternTest, VectorFMinOtherOrdered) {
+  parseAssembly(
+      "define <4 x float> @test(<4 x float> %a) {\n"
+      "  %1 = fcmp ole <4 x float> %a, \n"
+      "    <float 5.0, float 5.0, float 5.0, float 5.0>\n"
+      "  %A = select <4 x i1> %1, <4 x float> %a,\n"
+      "     <4 x float> <float 5.0, float 5.0, float 5.0, float 5.0>\n"
+      "  ret <4 x float> %A\n"
+      "}\n");
+  // Check that pattern matching works on vectors where each lane has the same
+  // ordered pattern.
+  expectPattern({SPF_FMINNUM, SPNB_RETURNS_OTHER, true});
+}
+
+TEST_F(MatchSelectPatternTest, VectorNotFMinNaN) {
+  parseAssembly(
+      "define <4 x float> @test(<4 x float> %a) {\n"
+      "  %1 = fcmp ule <4 x float> %a, \n"
+      "    <float 5.0, float 0x7ff8000000000000, float 5.0, float 5.0>\n"
+      "  %A = select <4 x i1> %1, <4 x float> %a,\n"
+      "     <4 x float> <float 5.0, float 0x7ff8000000000000, float 5.0, float "
+      "5.0>\n"
+      "  ret <4 x float> %A\n"
+      "}\n");
+  // The lane that contains a NaN (0x7ff80...) behaves like a
+  // non-NaN-propagating min and the other lines behave like a NaN-propagating
+  // min, so check that neither is returned.
+  expectPattern({SPF_UNKNOWN, SPNB_NA, false});
+}
+
+TEST_F(MatchSelectPatternTest, VectorNotFMinZero) {
+  parseAssembly(
+      "define <4 x float> @test(<4 x float> %a) {\n"
+      "  %1 = fcmp ule <4 x float> %a, \n"
+      "    <float 5.0, float -0.0, float 5.0, float 5.0>\n"
+      "  %A = select <4 x i1> %1, <4 x float> %a,\n"
+      "     <4 x float> <float 5.0, float 0.0, float 5.0, float 5.0>\n"
+      "  ret <4 x float> %A\n"
+      "}\n");
+  // Always selects the second lane of %a if it is positive or negative zero, so
+  // this is stricter than a min.
+  expectPattern({SPF_UNKNOWN, SPNB_NA, false});
+}
+
 TEST_F(MatchSelectPatternTest, DoubleCastU) {
   parseAssembly(
       "define i32 @test(i8 %a, i8 %b) {\n"