[llvm] cb02208 - ValueTracking: Handle fptrunc in computeKnownFPClass

[Matt Arsenault via llvm-commits]

Author: Matt Arsenault
Date: 2023-04-14T14:36:56-04:00
New Revision: cb022084f0a0422e1c8af39ab092ee9a1bc6fe9e

URL: https://github.com/llvm/llvm-project/commit/cb022084f0a0422e1c8af39ab092ee9a1bc6fe9e
DIFF: https://github.com/llvm/llvm-project/commit/cb022084f0a0422e1c8af39ab092ee9a1bc6fe9e.diff

LOG: ValueTracking: Handle fptrunc in computeKnownFPClass

Handle nan.

Added: 
    

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

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index 545ff49ba845..6f02be1bbb7d 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -4500,6 +4500,19 @@ void computeKnownFPClass(const Value *V, const APInt &DemandedElts,
 
     break;
   }
+  case Instruction::FPTrunc: {
+    if ((InterestedClasses & fcNan) == fcNone)
+      break;
+
+    KnownFPClass KnownSrc;
+    computeKnownFPClass(Op->getOperand(0), DemandedElts,
+                        InterestedClasses, KnownSrc, Depth + 1, Q, TLI);
+    if (KnownSrc.isKnownNeverNaN())
+      Known.knownNot(fcNan);
+
+    // Infinity needs a range check.
+    break;
+  }
   case Instruction::SIToFP:
   case Instruction::UIToFP: {
     // Cannot produce nan

diff  --git a/llvm/test/Transforms/Attributor/nofpclass-fptrunc.ll b/llvm/test/Transforms/Attributor/nofpclass-fptrunc.ll
index a486fcbd1520..2d6424fecccb 100644
--- a/llvm/test/Transforms/Attributor/nofpclass-fptrunc.ll
+++ b/llvm/test/Transforms/Attributor/nofpclass-fptrunc.ll
@@ -12,7 +12,7 @@ define float @ret_fptrunc(double %arg0) {
 }
 
 define float @ret_fptrunc_nonan(double nofpclass(nan) %arg0) {
-; CHECK-LABEL: define float @ret_fptrunc_nonan
+; CHECK-LABEL: define nofpclass(nan) float @ret_fptrunc_nonan
 ; CHECK-SAME: (double nofpclass(nan) [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fptrunc double [[ARG0]] to float
 ; CHECK-NEXT:    ret float [[EXT]]
@@ -102,7 +102,7 @@ define float @ret_fptrunc_nonzero(double nofpclass(nzero) %arg0) {
 }
 
 define float @ret_fptrunc_nonan_noinf(double nofpclass(nan inf) %arg0) {
-; CHECK-LABEL: define float @ret_fptrunc_nonan_noinf
+; CHECK-LABEL: define nofpclass(nan) float @ret_fptrunc_nonan_noinf
 ; CHECK-SAME: (double nofpclass(nan inf) [[ARG0:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:    [[EXT:%.*]] = fptrunc double [[ARG0]] to float
 ; CHECK-NEXT:    ret float [[EXT]]