Added TLI hook for isFPExtFree. Some of the FMA combine heuristics are now guarded with that hook.

llvm-svn: 225795

3 files changed, 77 insertions, 63 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 56ba91fbac5..171ee1e3488 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -6957,32 +6957,11 @@ SDValue DAGCombiner::visitFADD(SDNode *N) {
       return DAG.getNode(ISD::FMA, SDLoc(N), VT,
                          N1.getOperand(0), N1.getOperand(1), N0);
 
-    // More folding opportunities when target permits.
-    if (TLI.enableAggressiveFMAFusion(VT)) {
-      // fold (fadd (fma x, y, (fmul u, v)), z) -> (fma x, y (fma u, v, z))
-      if (N0.getOpcode() == ISD::FMA &&
-          N0.getOperand(2).getOpcode() == ISD::FMUL)
-        return DAG.getNode(ISD::FMA, SDLoc(N), VT,
-                           N0.getOperand(0), N0.getOperand(1),
-                           DAG.getNode(ISD::FMA, SDLoc(N), VT,
-                                       N0.getOperand(2).getOperand(0),
-                                       N0.getOperand(2).getOperand(1),
-                                       N1));
-
-      // fold (fadd x, (fma y, z, (fmul u, v)) -> (fma y, z (fma u, v, x))
-      if (N1->getOpcode() == ISD::FMA &&
-          N1.getOperand(2).getOpcode() == ISD::FMUL)
-        return DAG.getNode(ISD::FMA, SDLoc(N), VT,
-                           N1.getOperand(0), N1.getOperand(1),
-                           DAG.getNode(ISD::FMA, SDLoc(N), VT,
-                                       N1.getOperand(2).getOperand(0),
-                                       N1.getOperand(2).getOperand(1),
-                                       N0));
+    // When FP_EXTEND nodes are free on the target, and there is an opportunity
+    // to combine into FMA, arrange such nodes accordingly.
+    if (TLI.isFPExtFree(VT)) {
 
-      // Remove FP_EXTEND when there is an opportunity to combine. This is
-      // legal here since extra precision is allowed.
-
-      // fold (fadd (fpext (fmul x, y)), z) -> (fma x, y, z)
+      // fold (fadd (fpext (fmul x, y)), z) -> (fma (fpext x), (fpext y), z)
       if (N0.getOpcode() == ISD::FP_EXTEND) {
         SDValue N00 = N0.getOperand(0);
         if (N00.getOpcode() == ISD::FMUL)
@@ -6993,7 +6972,7 @@ SDValue DAGCombiner::visitFADD(SDNode *N) {
                                          N00.getOperand(1)), N1);
       }
 
-      // fold (fadd x, (fpext (fmul y, z)), z) -> (fma y, z, x)
+      // fold (fadd x, (fpext (fmul y, z)), z) -> (fma (fpext y), (fpext z), x)
       // Note: Commutes FADD operands.
       if (N1.getOpcode() == ISD::FP_EXTEND) {
         SDValue N10 = N1.getOperand(0);
@@ -7005,6 +6984,30 @@ SDValue DAGCombiner::visitFADD(SDNode *N) {
                                          N10.getOperand(1)), N0);
       }
     }
+
+    // More folding opportunities when target permits.
+    if (TLI.enableAggressiveFMAFusion(VT)) {
+
+      // fold (fadd (fma x, y, (fmul u, v)), z) -> (fma x, y (fma u, v, z))
+      if (N0.getOpcode() == ISD::FMA &&
+          N0.getOperand(2).getOpcode() == ISD::FMUL)
+        return DAG.getNode(ISD::FMA, SDLoc(N), VT,
+                           N0.getOperand(0), N0.getOperand(1),
+                           DAG.getNode(ISD::FMA, SDLoc(N), VT,
+                                       N0.getOperand(2).getOperand(0),
+                                       N0.getOperand(2).getOperand(1),
+                                       N1));
+
+      // fold (fadd x, (fma y, z, (fmul u, v)) -> (fma y, z (fma u, v, x))
+      if (N1->getOpcode() == ISD::FMA &&
+          N1.getOperand(2).getOpcode() == ISD::FMUL)
+        return DAG.getNode(ISD::FMA, SDLoc(N), VT,
+                           N1.getOperand(0), N1.getOperand(1),
+                           DAG.getNode(ISD::FMA, SDLoc(N), VT,
+                                       N1.getOperand(2).getOperand(0),
+                                       N1.getOperand(2).getOperand(1),
+                                       N0));
+    }
   }
 
   return SDValue();
@@ -7099,41 +7102,12 @@ SDValue DAGCombiner::visitFSUB(SDNode *N) {
                          DAG.getNode(ISD::FNEG, dl, VT, N1));
     }
 
-    // More folding opportunities when target permits.
-    if (TLI.enableAggressiveFMAFusion(VT)) {
+    // When FP_EXTEND nodes are free on the target, and there is an opportunity
+    // to combine into FMA, arrange such nodes accordingly.
+    if (TLI.isFPExtFree(VT)) {
 
-      // fold (fsub (fma x, y, (fmul u, v)), z)
-      //   -> (fma x, y (fma u, v, (fneg z)))
-      if (N0.getOpcode() == ISD::FMA &&
-          N0.getOperand(2).getOpcode() == ISD::FMUL)
-        return DAG.getNode(ISD::FMA, SDLoc(N), VT,
-                           N0.getOperand(0), N0.getOperand(1),
-                           DAG.getNode(ISD::FMA, SDLoc(N), VT,
-                                       N0.getOperand(2).getOperand(0),
-                                       N0.getOperand(2).getOperand(1),
-                                       DAG.getNode(ISD::FNEG, SDLoc(N), VT,
-                                                   N1)));
-
-      // fold (fsub x, (fma y, z, (fmul u, v)))
-      //   -> (fma (fneg y), z, (fma (fneg u), v, x))
-      if (N1.getOpcode() == ISD::FMA &&
-          N1.getOperand(2).getOpcode() == ISD::FMUL) {
-        SDValue N20 = N1.getOperand(2).getOperand(0);
-        SDValue N21 = N1.getOperand(2).getOperand(1);
-        return DAG.getNode(ISD::FMA, SDLoc(N), VT,
-                           DAG.getNode(ISD::FNEG, SDLoc(N), VT,
-                                       N1.getOperand(0)),
-                           N1.getOperand(1),
-                           DAG.getNode(ISD::FMA, SDLoc(N), VT,
-                                       DAG.getNode(ISD::FNEG, SDLoc(N),  VT,
-                                                   N20),
-                                       N21, N0));
-      }
-
-      // Remove FP_EXTEND when there is an opportunity to combine. This is
-      // legal here since extra precision is allowed.
-
-      // fold (fsub (fpext (fmul x, y)), z) -> (fma x, y, (fneg z))
+      // fold (fsub (fpext (fmul x, y)), z)
+      //   -> (fma (fpext x), (fpext y), (fneg z))
       if (N0.getOpcode() == ISD::FP_EXTEND) {
         SDValue N00 = N0.getOperand(0);
         if (N00.getOpcode() == ISD::FMUL)
@@ -7145,7 +7119,8 @@ SDValue DAGCombiner::visitFSUB(SDNode *N) {
                              DAG.getNode(ISD::FNEG, SDLoc(N), VT, N1));
       }
 
-      // fold (fsub x, (fpext (fmul y, z))) -> (fma (fneg y), z, x)
+      // fold (fsub x, (fpext (fmul y, z)))
+      //   -> (fma (fneg (fpext y)), (fpext z), x)
       // Note: Commutes FSUB operands.
       if (N1.getOpcode() == ISD::FP_EXTEND) {
         SDValue N10 = N1.getOperand(0);
@@ -7160,7 +7135,7 @@ SDValue DAGCombiner::visitFSUB(SDNode *N) {
       }
 
       // fold (fsub (fpext (fneg (fmul, x, y))), z)
-      //   -> (fma (fneg x), y, (fneg z))
+      //   -> (fma (fneg (fpext x)), (fpext y), (fneg z))
       if (N0.getOpcode() == ISD::FP_EXTEND) {
         SDValue N00 = N0.getOperand(0);
         if (N00.getOpcode() == ISD::FNEG) {
@@ -7178,7 +7153,7 @@ SDValue DAGCombiner::visitFSUB(SDNode *N) {
       }
 
       // fold (fsub (fneg (fpext (fmul, x, y))), z)
-      //   -> (fma (fneg x), y, (fneg z))
+      //   -> (fma (fneg (fpext x)), (fpext y), (fneg z))
       if (N0.getOpcode() == ISD::FNEG) {
         SDValue N00 = N0.getOperand(0);
         if (N00.getOpcode() == ISD::FP_EXTEND) {
@@ -7195,6 +7170,38 @@ SDValue DAGCombiner::visitFSUB(SDNode *N) {
         }
       }
     }
+
+    // More folding opportunities when target permits.
+    if (TLI.enableAggressiveFMAFusion(VT)) {
+
+      // fold (fsub (fma x, y, (fmul u, v)), z)
+      //   -> (fma x, y (fma u, v, (fneg z)))
+      if (N0.getOpcode() == ISD::FMA &&
+          N0.getOperand(2).getOpcode() == ISD::FMUL)
+        return DAG.getNode(ISD::FMA, SDLoc(N), VT,
+                           N0.getOperand(0), N0.getOperand(1),
+                           DAG.getNode(ISD::FMA, SDLoc(N), VT,
+                                       N0.getOperand(2).getOperand(0),
+                                       N0.getOperand(2).getOperand(1),
+                                       DAG.getNode(ISD::FNEG, SDLoc(N), VT,
+                                                   N1)));
+
+      // fold (fsub x, (fma y, z, (fmul u, v)))
+      //   -> (fma (fneg y), z, (fma (fneg u), v, x))
+      if (N1.getOpcode() == ISD::FMA &&
+          N1.getOperand(2).getOpcode() == ISD::FMUL) {
+        SDValue N20 = N1.getOperand(2).getOperand(0);
+        SDValue N21 = N1.getOperand(2).getOperand(1);
+        return DAG.getNode(ISD::FMA, SDLoc(N), VT,
+                           DAG.getNode(ISD::FNEG, SDLoc(N), VT,
+                                       N1.getOperand(0)),
+                           N1.getOperand(1),
+                           DAG.getNode(ISD::FMA, SDLoc(N), VT,
+                                       DAG.getNode(ISD::FNEG, SDLoc(N),  VT,
+                                                   N20),
+                                       N21, N0));
+      }
+    }
   }
 
   return SDValue();
diff --git a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
index 30f08d050da..2157003ef3e 100644
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -9817,6 +9817,11 @@ bool PPCTargetLowering::isZExtFree(SDValue Val, EVT VT2) const {
   return TargetLowering::isZExtFree(Val, VT2);
 }
 
+bool PPCTargetLowering::isFPExtFree(EVT VT) const {
+  assert(VT.isFloatingPoint());
+  return true;
+}
+
 bool PPCTargetLowering::isLegalICmpImmediate(int64_t Imm) const {
   return isInt<16>(Imm) || isUInt<16>(Imm);
 }
diff --git a/llvm/lib/Target/PowerPC/PPCISelLowering.h b/llvm/lib/Target/PowerPC/PPCISelLowering.h
index db5a3e42d52..b171b165877 100644
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.h
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.h
@@ -528,6 +528,8 @@ namespace llvm {
 
     bool isZExtFree(SDValue Val, EVT VT2) const override;
 
+    bool isFPExtFree(EVT VT) const override;
+
     /// \brief Returns true if it is beneficial to convert a load of a constant
     /// to just the constant itself.
     bool shouldConvertConstantLoadToIntImm(const APInt &Imm,