[PATCH] D14076: [FPEnv Core 11/14] Don't convert fpops to constexprs in SCCP

[Sergey Dmitrouk via llvm-commits]

sdmitrouk created this revision.
sdmitrouk added reviewers: hfinkel, joker.eph.
sdmitrouk added subscribers: llvm-commits, resistor, scanon.
sdmitrouk set the repository for this revision to rL LLVM.

Repository:
  rL LLVM

http://reviews.llvm.org/D14076

Files:
  lib/Transforms/Scalar/SCCP.cpp
  test/Transforms/SCCP/do-not-convert-fpop-to-constexpr.ll

Index: test/Transforms/SCCP/do-not-convert-fpop-to-constexpr.ll
===================================================================
--- /dev/null
+++ test/Transforms/SCCP/do-not-convert-fpop-to-constexpr.ll
@@ -0,0 +1,24 @@
+; fmuls shouldn't be converted to constant expressions.
+; RUN: opt < %s -sccp -S -enable-except-access-fp-math | FileCheck %s
+
+define double @do-not-convert-fpop-to-constexpr(double %x) {
+; CHECK-LABEL: @do-not-convert-fpop-to-constexpr(
+; CHECK: fmul
+; CHECK: fmul
+; CHECK-NOT: select
+entry:
+  %cmp = fcmp oeq double %x, 0.000000e+00
+  br i1 %cmp, label %cond.true, label %cond.false
+
+cond.true:
+  %val.true = fmul kexc double 1.000000e+300, 1.000000e+300
+  br label %cond.end
+
+cond.false:
+  %val.false = fmul kexc double 1.000000e-300, 1.000000e-300
+  br label %cond.end
+
+cond.end:
+  %cond = phi double [ %val.true, %cond.true ], [ %val.false, %cond.false ]
+  ret double %cond
+}
Index: lib/Transforms/Scalar/SCCP.cpp
===================================================================
--- lib/Transforms/Scalar/SCCP.cpp
+++ lib/Transforms/Scalar/SCCP.cpp
@@ -857,10 +857,18 @@
   LatticeVal &IV = ValueState[&I];
   if (IV.isOverdefined()) return;
 
-  if (V1State.isConstant() && V2State.isConstant())
-    return markConstant(IV, &I,
-                        ConstantExpr::get(I.getOpcode(), V1State.getConstant(),
-                                          V2State.getConstant()));
+  if (V1State.isConstant() && V2State.isConstant()) {
+    FastMathFlags FMF;
+
+    if (isa<FPMathOperator>(&I)) {
+      FMF = I.getFastMathFlags();
+    }
+
+    if (Constant *C = ConstantExpr::get(I.getOpcode(), V1State.getConstant(),
+                                        V2State.getConstant(), 0, nullptr,
+                                        FMF, true))
+      return markConstant(IV, &I, C);
+  }
 
   // If something is undef, wait for it to resolve.
   if (!V1State.isOverdefined() && !V2State.isOverdefined())


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