TableGen: Fix logic for default operands

This was checking for default operands in the current DAG instruction,
rather than the correct result operand list. I'm not entirly sure how
this managed to work before, but was failing for me when multiple
default operands were overridden.

llvm/test/TableGen/DefaultOpsGlobalISel.td

@@ -7,6 +7,7 @@ include "GlobalISelEmitterCommon.td"
 def SelectClamp  : ComplexPattern<untyped, 2, "SelectClamp">;
 def SelectOMod  : ComplexPattern<untyped, 2, "SelectOMod">;
 def SelectClampOMod  : ComplexPattern<untyped, 3, "SelectClampOMod">;
+def SelectSrcMods  : ComplexPattern<untyped, 2, "SelectSrcMods">;
 
 def gi_SelectClamp :
     GIComplexOperandMatcher<s32, "selectClamp">,
@@ -20,11 +21,29 @@ def gi_SelectClampOMod :
     GIComplexOperandMatcher<s32, "selectClampOMod">,
     GIComplexPatternEquiv<SelectClampOMod>;
 
+def gi_SelectSrcMods :
+    GIComplexOperandMatcher<s32, "selectSrcMods">,
+    GIComplexPatternEquiv<SelectSrcMods>;
 
+
+def src_mods : Operand <i32>;
 def omod : OperandWithDefaultOps <i32, (ops (i32 0))>;
 def clamp : OperandWithDefaultOps <i1, (ops (i1 0))>;
 
 
+// CHECK: GIM_CheckOpcode, /*MI*/0, TargetOpcode::G_FMAXNUM,
+// CHECK: GIM_CheckComplexPattern, /*MI*/0, /*Op*/1, /*Renderer*/0, GICP_gi_SelectSrcMods,
+// CHECK: GIM_CheckComplexPattern, /*MI*/0, /*Op*/2, /*Renderer*/1, GICP_gi_SelectSrcMods,
+// CHECK: GIR_BuildMI, /*InsnID*/0, /*Opcode*/MyTarget::FMAX,
+// CHECK-NEXT: GIR_Copy, /*NewInsnID*/0, /*OldInsnID*/0, /*OpIdx*/0, // dst
+// CHECK-NEXT: GIR_ComplexSubOperandRenderer, /*InsnID*/0, /*RendererID*/0, /*SubOperand*/1, // mods0
+// CHECK-NEXT: GIR_ComplexSubOperandRenderer, /*InsnID*/0, /*RendererID*/0, /*SubOperand*/0, // src0
+// CHECK-NEXT: GIR_ComplexSubOperandRenderer, /*InsnID*/0, /*RendererID*/1, /*SubOperand*/1, // mods1
+// CHECK-NEXT: GIR_ComplexSubOperandRenderer, /*InsnID*/0, /*RendererID*/1, /*SubOperand*/0, // src1
+// CHECK-NEXT: GIR_AddImm, /*InsnID*/0, /*Imm*/0,
+// CHECK-NEXT: GIR_EraseFromParent, /*InsnID*/0,
+
+
 // CHECK: GIM_CheckOpcode, /*MI*/0, TargetOpcode::G_FFLOOR,
 // CHECK: GIM_CheckComplexPattern, /*MI*/0, /*Op*/1, /*Renderer*/0, GICP_gi_SelectClampOMod,
 // CHECK: // (ffloor:{ *:[f32] } (SelectClampOMod:{ *:[f32] } f32:{ *:[f32] }:$src0, omod:{ *:[i32] }:$omod, i1:{ *:[i1] }:$clamp))  =>  (FLOMP:{ *:[f32] } f32:{ *:[f32] }:$src0, i1:{ *:[i1] }:$clamp, omod:{ *:[i32] }:$omod)
@@ -35,6 +54,17 @@ def clamp : OperandWithDefaultOps <i1, (ops (i1 0))>;
 // CHECK-NEXT: GIR_ComplexSubOperandRenderer, /*InsnID*/0, /*RendererID*/0, /*SubOperand*/1, // omod
 
 
+// CHECK: GIM_CheckOpcode, /*MI*/0, TargetOpcode::G_FCANONICALIZE,
+// CHECK: GIR_BuildMI, /*InsnID*/0, /*Opcode*/MyTarget::FMAX,
+// CHECK-NEXT: GIR_Copy, /*NewInsnID*/0, /*OldInsnID*/0, /*OpIdx*/0, // dst
+// CHECK-NEXT: GIR_ComplexSubOperandRenderer, /*InsnID*/0, /*RendererID*/0, /*SubOperand*/1, // mods
+// CHECK-NEXT: GIR_ComplexSubOperandRenderer, /*InsnID*/0, /*RendererID*/0, /*SubOperand*/0, // src
+// CHECK-NEXT: GIR_ComplexSubOperandRenderer, /*InsnID*/0, /*RendererID*/0, /*SubOperand*/1, // mods
+// CHECK-NEXT: GIR_ComplexSubOperandRenderer, /*InsnID*/0, /*RendererID*/0, /*SubOperand*/0, // src
+// CHECK-NEXT: GIR_AddImm, /*InsnID*/0, /*Imm*/0,
+// CHECK-NEXT: GIR_EraseFromParent, /*InsnID*/0,
+
+
 // CHECK: GIM_CheckOpcode, /*MI*/0, TargetOpcode::G_FCOS,
 // CHECK: // (fcos:{ *:[f32] } (SelectOMod:{ *:[f32] } f32:{ *:[f32] }:$src0, i32:{ *:[i32] }:$omod))  =>  (FLAMP:{ *:[f32] } FPR32:{ *:[f32] }:$src0, omod:{ *:[i32] }:$omod)
 // CHECK-NEXT: GIR_BuildMI, /*InsnID*/0, /*Opcode*/MyTarget::FLAMP,
@@ -142,3 +172,16 @@ def : Pat <
   (fexp2 (SelectClamp f32:$src0, i1:$clamp)),
   (FEEPLE FPR32:$src0, (FFOO FPR32:$src0), clamp:$clamp)
 >;
+
+// Same instruction is used in two different pattern contexts, one
+// uses the default and one does not.
+def FMAX : I<(outs FPR32:$dst),
+  (ins src_mods:$mods0, FPR32:$src0, src_mods:$mods1, FPR32:$src1, clamp:$clamp),
+  [(set FPR32:$dst, (f32 (fmaxnum (SelectSrcMods f32:$src0, src_mods:$mods0),
+                                  (SelectSrcMods f32:$src1, src_mods:$mods1))))]
+>;
+
+def : Pat<
+  (fcanonicalize (f32 (SelectSrcMods f32:$src, i32:$mods))),
+  (FMAX $mods, $src, $mods, $src, 0)
+>;

llvm/utils/TableGen/CodeGenDAGPatterns.cpp

@@ -2520,6 +2520,9 @@ bool TreePatternNode::ApplyTypeConstraints(TreePattern &TP, bool NotRegisters) {
       }
     }
 
+    unsigned NumResults = Inst.getNumResults();
+    unsigned NumFixedOperands = InstInfo.Operands.size();
+
     // If one or more operands with a default value appear at the end of the
     // formal operand list for an instruction, we allow them to be overridden
     // by optional operands provided in the pattern.
@@ -2528,14 +2531,15 @@ bool TreePatternNode::ApplyTypeConstraints(TreePattern &TP, bool NotRegisters) {
     // operand A with a default, then we don't allow A to be overridden,
     // because there would be no way to specify whether the next operand in
     // the pattern was intended to override A or skip it.
-    unsigned NonOverridableOperands = Inst.getNumOperands();
-    while (NonOverridableOperands > 0 &&
-           CDP.operandHasDefault(Inst.getOperand(NonOverridableOperands-1)))
+    unsigned NonOverridableOperands = NumFixedOperands;
+    while (NonOverridableOperands > NumResults &&
+           CDP.operandHasDefault(InstInfo.Operands[NonOverridableOperands-1].Rec))
       --NonOverridableOperands;
 
     unsigned ChildNo = 0;
-    for (unsigned i = 0, e = Inst.getNumOperands(); i != e; ++i) {
-      Record *OperandNode = Inst.getOperand(i);
+    assert(NumResults <= NumFixedOperands);
+    for (unsigned i = NumResults, e = NumFixedOperands; i != e; ++i) {
+      Record *OperandNode = InstInfo.Operands[i].Rec;
 
       // If the operand has a default value, do we use it? We must use the
       // default if we've run out of children of the pattern DAG to consume,