[llvm] dd61b63 - ValueTracking: Handle sign bit for fptrunc in computeKnownFPClass

[Matt Arsenault via llvm-commits]

Author: Matt Arsenault
Date: 2023-05-17T23:40:06+01:00
New Revision: dd61b63b5ca1c8a15013e2154bf3b30243df66bd

URL: https://github.com/llvm/llvm-project/commit/dd61b63b5ca1c8a15013e2154bf3b30243df66bd
DIFF: https://github.com/llvm/llvm-project/commit/dd61b63b5ca1c8a15013e2154bf3b30243df66bd.diff

LOG: ValueTracking: Handle sign bit for fptrunc in computeKnownFPClass

Added: 
    

Modified: 
    llvm/include/llvm/Analysis/ValueTracking.h
    llvm/lib/Analysis/ValueTracking.cpp
    llvm/test/Transforms/Attributor/nofpclass-fptrunc.ll

Removed: 
    


################################################################################
diff  --git a/llvm/include/llvm/Analysis/ValueTracking.h b/llvm/include/llvm/Analysis/ValueTracking.h
index e6609f2e0073..92781c598a59 100644
--- a/llvm/include/llvm/Analysis/ValueTracking.h
+++ b/llvm/include/llvm/Analysis/ValueTracking.h
@@ -323,7 +323,7 @@ struct KnownFPClass {
   ///   x > +0 --> true
   ///   x < -0 --> false
   bool cannotBeOrderedLessThanZero() const {
-  return isKnownNever(OrderedLessThanZeroMask);
+    return isKnownNever(OrderedLessThanZeroMask);
   }
 
   /// Return true if we can prove that the analyzed floating-point value is

diff  --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index 37414de4c240..05ed497b7601 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -4617,17 +4617,22 @@ static void computeKnownFPClassForFPTrunc(const Operator *Op,
                                           KnownFPClass &Known, unsigned Depth,
                                           const Query &Q,
                                           const TargetLibraryInfo *TLI) {
-  if ((InterestedClasses & fcNan) == fcNone)
+  if ((InterestedClasses &
+       (KnownFPClass::OrderedLessThanZeroMask | fcNan)) == fcNone)
     return;
 
   KnownFPClass KnownSrc;
   computeKnownFPClass(Op->getOperand(0), DemandedElts, InterestedClasses,
                       KnownSrc, Depth + 1, Q, TLI);
-  if (KnownSrc.isKnownNeverNaN())
-    Known.knownNot(fcNan);
+
+  // Sign should be preserved
+  // TODO: Handle cannot be ordered greater than zero
+  if (KnownSrc.cannotBeOrderedLessThanZero())
+    Known.knownNot(KnownFPClass::OrderedLessThanZeroMask);
+
+  Known.propagateNaN(KnownSrc, true);
 
   // Infinity needs a range check.
-  // TODO: Sign bit should be preserved
 }
 
 // TODO: Merge implementations of isKnownNeverNaN, isKnownNeverInfinity,

diff  --git a/llvm/test/Transforms/Attributor/nofpclass-fptrunc.ll b/llvm/test/Transforms/Attributor/nofpclass-fptrunc.ll
index 9274114611a8..2e9c30b42b41 100644
--- a/llvm/test/Transforms/Attributor/nofpclass-fptrunc.ll
+++ b/llvm/test/Transforms/Attributor/nofpclass-fptrunc.ll
@@ -34,7 +34,7 @@ define float @ret_fptrunc_noqnan(double nofpclass(qnan) %arg0) {
 }
 
 define float @ret_fptrunc_nosnan(double nofpclass(snan) %arg0) {
-; CHECK-LABEL: define float @ret_fptrunc_nosnan
+; CHECK-LABEL: define nofpclass(snan) float @ret_fptrunc_nosnan
 ; CHECK-SAME: (double nofpclass(snan) [[ARG0:%.*]]) #[[ATTR1]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fptrunc double [[ARG0]] to float
 ; CHECK-NEXT:    ret float [[EXT]]
@@ -134,7 +134,7 @@ define float @ret_fptrunc_nonorm(double nofpclass(norm) %arg0) {
 }
 
 define float @ret_fptrunc_posonly(double nofpclass(ninf nnorm nsub nzero) %arg0) {
-; CHECK-LABEL: define float @ret_fptrunc_posonly
+; CHECK-LABEL: define nofpclass(ninf nsub nnorm) float @ret_fptrunc_posonly
 ; CHECK-SAME: (double nofpclass(ninf nzero nsub nnorm) [[ARG0:%.*]]) #[[ATTR1]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fptrunc double [[ARG0]] to float
 ; CHECK-NEXT:    ret float [[EXT]]
@@ -144,7 +144,7 @@ define float @ret_fptrunc_posonly(double nofpclass(ninf nnorm nsub nzero) %arg0)
 }
 
 define float @ret_fptrunc_posonly_zero(double nofpclass(ninf nnorm nsub) %arg0) {
-; CHECK-LABEL: define float @ret_fptrunc_posonly_zero
+; CHECK-LABEL: define nofpclass(ninf nsub nnorm) float @ret_fptrunc_posonly_zero
 ; CHECK-SAME: (double nofpclass(ninf nsub nnorm) [[ARG0:%.*]]) #[[ATTR1]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fptrunc double [[ARG0]] to float
 ; CHECK-NEXT:    ret float [[EXT]]
@@ -154,7 +154,7 @@ define float @ret_fptrunc_posonly_zero(double nofpclass(ninf nnorm nsub) %arg0)
 }
 
 define float @ret_fptrunc_posonly_zero_nan(double nofpclass(ninf nnorm nsub nan) %arg0) {
-; CHECK-LABEL: define nofpclass(nan) float @ret_fptrunc_posonly_zero_nan
+; CHECK-LABEL: define nofpclass(nan ninf nsub nnorm) float @ret_fptrunc_posonly_zero_nan
 ; CHECK-SAME: (double nofpclass(nan ninf nsub nnorm) [[ARG0:%.*]]) #[[ATTR1]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fptrunc double [[ARG0]] to float
 ; CHECK-NEXT:    ret float [[EXT]]
@@ -164,7 +164,7 @@ define float @ret_fptrunc_posonly_zero_nan(double nofpclass(ninf nnorm nsub nan)
 }
 
 define float @ret_fptrunc_posonly_nan(double nofpclass(ninf nnorm nsub nzero nan) %arg0) {
-; CHECK-LABEL: define nofpclass(nan) float @ret_fptrunc_posonly_nan
+; CHECK-LABEL: define nofpclass(nan ninf nsub nnorm) float @ret_fptrunc_posonly_nan
 ; CHECK-SAME: (double nofpclass(nan ninf nzero nsub nnorm) [[ARG0:%.*]]) #[[ATTR1]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fptrunc double [[ARG0]] to float
 ; CHECK-NEXT:    ret float [[EXT]]
@@ -234,9 +234,9 @@ define float @ret_fptrunc_round_noqnan(double nofpclass(qnan) %arg0) {
 }
 
 define float @ret_fptrunc_round_nosnan(double nofpclass(snan) %arg0) {
-; CHECK-LABEL: define float @ret_fptrunc_round_nosnan
+; CHECK-LABEL: define nofpclass(snan) float @ret_fptrunc_round_nosnan
 ; CHECK-SAME: (double nofpclass(snan) [[ARG0:%.*]]) #[[ATTR1]] {
-; CHECK-NEXT:    [[EXT:%.*]] = call float @llvm.fptrunc.round.f32.f64(double [[ARG0]], metadata !"round.downward") #[[ATTR2]]
+; CHECK-NEXT:    [[EXT:%.*]] = call nofpclass(snan) float @llvm.fptrunc.round.f32.f64(double [[ARG0]], metadata !"round.downward") #[[ATTR2]]
 ; CHECK-NEXT:    ret float [[EXT]]
 ;
   %ext = call float @llvm.fptrunc.round.f32.f64(double %arg0, metadata !"round.downward")