[PATCH] D147733: Set rounding_mode to tonearest in presence of a #pragma STDC FENV_ACCESS OFF.

[Zahira Ammarguellat via Phabricator via cfe-commits]

zahiraam created this revision.
zahiraam added reviewers: andrew.w.kaylor, pengfei.
Herald added a project: All.
zahiraam requested review of this revision.
Herald added a project: clang.

In strict mode the 'roundin_mode' is set to 'dynamic'. Using this pragma to get out of strict mode doesn't have any effect on the 'rounding_mode'.
See https://godbolt.org/z/zoGTf4j1G
This patch fixes that.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D147733

Files:
  clang/include/clang/Basic/LangOptions.h
  clang/lib/Sema/SemaAttr.cpp
  clang/test/CodeGen/pragma-fenv_access.c


Index: clang/test/CodeGen/pragma-fenv_access.c
===================================================================
--- clang/test/CodeGen/pragma-fenv_access.c
+++ clang/test/CodeGen/pragma-fenv_access.c
@@ -224,3 +224,17 @@
 // STRICT: call float @llvm.experimental.constrained.fadd.f32(float {{.*}}, float {{.*}}, metadata !"round.tonearest", metadata !"fpexcept.strict")
 // DEFAULT: fadd float
 
+#pragma STDC FENV_ACCESS ON
+float func_19(float x, float y) {
+  return x + y;
+}
+// CHECK-LABEL: @func_19
+// STRICT:  call float @llvm.experimental.constrained.fadd.f32(float %0, float %1, metadata !"round.dynamic", metadata !"fpexcept.strict")
+
+#pragma STDC FENV_ACCESS OFF
+float func_20(float x, float y) {
+  return x + y;
+}
+// CHECK-LABEL: @func_20
+// STRICT: call float @llvm.experimental.constrained.fadd.f32(float {{.*}}, float {{.*}}, metadata !"round.tonearest", metadata !"fpexcept.strict")
+// DEFAULT: fadd float
Index: clang/lib/Sema/SemaAttr.cpp
===================================================================
--- clang/lib/Sema/SemaAttr.cpp
+++ clang/lib/Sema/SemaAttr.cpp
@@ -1336,6 +1336,8 @@
       Diag(Loc, diag::err_pragma_fenv_requires_precise);
   }
   NewFPFeatures.setAllowFEnvAccessOverride(IsEnabled);
+  if (!IsEnabled)
+    NewFPFeatures.setDisallowFenvAccess(IsEnabled);
   FpPragmaStack.Act(Loc, PSK_Set, StringRef(), NewFPFeatures);
   CurFPFeatures = NewFPFeatures.applyOverrides(getLangOpts());
 }
Index: clang/include/clang/Basic/LangOptions.h
===================================================================
--- clang/include/clang/Basic/LangOptions.h
+++ clang/include/clang/Basic/LangOptions.h
@@ -843,6 +843,10 @@
     setFPContractModeOverride(LangOptions::FPM_Off);
   }
 
+  void setDisallowFenvAccess(bool Value) {
+    setRoundingMathOverride(Value);
+  }
+
   void setFPPreciseEnabled(bool Value) {
     setAllowFPReassociateOverride(!Value);
     setNoHonorNaNsOverride(!Value);


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