mibintc added a comment.
I neglected to hit the "submit" button last week, these are the inline
questions I have.
Also in addition to the comments above, check-clang is showing 1 LIT test
failing AST/const-fpfeatures.cpp
I believe the clang constant folder is returning False for the expression, and
the constant folding is being done by the LLVM constant folder
llvm-project/clang/test/AST/const-fpfeatures.cpp:21:11: error: CHECK: expected
string not found in input
// CHECK: @V1 = {{.*}} float 1.000000e+00
^
<stdin>:1:1: note: scanning from here
; ModuleID =
'/export/iusers/mblower/sandbox/llorg/llvm-project/clang/test/AST/const-fpfeatures.cpp'
^
<stdin>:24:1: note: possible intended match here
@V1 = global float 0.000000e+00, align 4
The reason i think clang constant folder/my patch/ isn't to blame for faulty
logic is because if I change the test to make V1 constexpr, there is an error
message "not constant". So i'm not sure if the bug is in clang or the test case
needs to be fixed?
================
Comment at: clang/lib/AST/ExprConstant.cpp:2734
if (LHS.isNaN()) {
- Info.CCEDiag(E, diag::note_constexpr_float_arithmetic) << LHS.isNaN();
+ Info.FFDiag(E, diag::note_constexpr_float_arithmetic) << LHS.isNaN();
return Info.noteUndefinedBehavior();
----------------
This should be FFDiag?
================
Comment at: clang/lib/AST/ExprConstant.cpp:12302
+ E->getFPFeaturesInEffect(Info.Ctx.getLangOpts()).isFPConstrained()) {
+ // Note: Compares may raise invalid in some cases involving NaN or sNaN.
+ Info.FFDiag(E, diag::note_constexpr_float_arithmetic_strict);
----------------
My scribbled notes say "ISO 10967 LIA-1
Equality returns invalid if either operand is signaling NaN
Other comparisons < <= >= > return invalid if either operand is NaN". I'm not
putting my hands on the exact reference.
================
Comment at: clang/test/CodeGen/pragma-fenv_access.c:9
+// CHECK-LABEL: @func_01
+// CHECK: call float @llvm.experimental.constrained.fadd.f32(float {{.*}},
float {{.*}}, metadata !"round.tonearest", metadata !"fpexcept.strict")
+
----------------
sepavloff wrote:
> Shall the rounding mode be `dynamic` rather than `tonearest`? If `#pragma
> STDC FENV_ACCESS ON` is specified, it means FP environment may be changed in
> arbitrary way and we cannot expect any particular rounding mode. Probably the
> environment was changed in the caller of `func_01`.
Yes thanks @sepavloff ! i made this change
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D87528/new/
https://reviews.llvm.org/D87528
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