[PATCH] D90288: [FPEnv] Allow strict SETCC falling back if strict FP is not supported.

[Pengfei Wang via Phabricator via llvm-commits]

pengfei created this revision.
pengfei added reviewers: uweigand, kpn, craig.topper, cameron.mcinally, andrew.w.kaylor, mibintc, sunfish.
Herald added subscribers: llvm-commits, hiraditya, jgravelle-google, sbc100, dschuff.
Herald added a project: LLVM.
pengfei requested review of this revision.
Herald added a subscriber: aheejin.

This patch fix bug: https://bugs.llvm.org/show_bug.cgi?id=47990


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D90288

Files:
  llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
  llvm/test/CodeGen/WebAssembly/pr47990.ll


Index: llvm/test/CodeGen/WebAssembly/pr47990.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/WebAssembly/pr47990.ll
@@ -0,0 +1,29 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s | FileCheck %s
+
+target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
+target triple = "wasm32-unknown-wasi"
+
+ at b = global double 0.000000e+00, align 8
+ at a = global double 0.000000e+00, align 8
+
+define i32 @c() nounwind strictfp {
+; CHECK-LABEL: c:
+; CHECK:         .functype c () -> (i32)
+; CHECK-NEXT:  # %bb.0: # %entry
+; CHECK-NEXT:    global.get __stack_pointer
+; CHECK-NEXT:    i32.const 16
+; CHECK-NEXT:    i32.sub
+; CHECK-NEXT:    i32.load 12
+; CHECK-NEXT:    # fallthrough-return
+entry:
+  %retval = alloca i32, align 4
+  %0 = load double, double* @b, align 8
+  %1 = load double, double* @a, align 8
+  %cmp = call i1 @llvm.experimental.constrained.fcmp.f64(double %0, double %1, metadata !"oeq", metadata !"fpexcept.strict") strictfp
+  %conv = zext i1 %cmp to i32
+  %2 = load i32, i32* %retval, align 4
+  ret i32 %2
+}
+
+declare i1 @llvm.experimental.constrained.fcmp.f64(double, double, metadata, metadata) strictfp
Index: llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
===================================================================
--- llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -3759,9 +3759,18 @@
       break;
     }
 
-    // FIXME: It seems Legalized is false iff CCCode is Legal. I don't
-    // understand if this code is useful for strict nodes.
-    assert(!IsStrict && "Don't know how to expand for strict nodes.");
+    if (IsStrict) {
+      MVT OpVT = Tmp1.getSimpleValueType();
+      // FIXME: For now, we just fall back to the non-strict version if SETCC is
+      // legal on the target.
+      if (!TLI.isStrictFPEnabled() &&
+          TLI.getOperationAction(ISD::SETCC, OpVT) == TargetLowering::Legal)
+        return true;
+
+      // FIXME: We may need to add STRICT_FSELECT_CC and STRICT_FSELECT_CCS
+      // handing for target that only supports SELECT_CC.
+      assert("Expanding to SELECT_CC is not supported for strict nodes.");
+    }
 
     // Otherwise, SETCC for the given comparison type must be completely
     // illegal; expand it into a SELECT_CC.
@@ -3785,7 +3794,7 @@
     break;
   }
   case ISD::SELECT_CC: {
-    // TODO: need to add STRICT_SELECT_CC and STRICT_SELECT_CCS
+    // TODO: need to add STRICT_FSELECT_CC and STRICT_FSELECT_CCS
     Tmp1 = Node->getOperand(0);   // LHS
     Tmp2 = Node->getOperand(1);   // RHS
     Tmp3 = Node->getOperand(2);   // True
@@ -3860,7 +3869,7 @@
     break;
   }
   case ISD::BR_CC: {
-    // TODO: need to add STRICT_BR_CC and STRICT_BR_CCS
+    // TODO: need to add STRICT_FBR_CC and STRICT_FBR_CCS
     SDValue Chain;
     Tmp1 = Node->getOperand(0);              // Chain
     Tmp2 = Node->getOperand(2);              // LHS


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