Add intrinsics for constrained floating point operations

This commit introduces a set of experimental intrinsics intended to prevent
optimizations that make assumptions about the rounding mode and floating point
exception behavior.  These intrinsics will later be extended to specify
flush-to-zero behavior.  More work is also required to model instruction
dependencies in machine code and to generate these instructions from clang
(when required by pragmas and/or command line options that are not currently
supported).

Differential Revision: https://reviews.llvm.org/D27028

llvm-svn: 293226

1 files changed, 43 insertions, 0 deletions

diff --git a/llvm/test/Verifier/fp-intrinsics.ll b/llvm/test/Verifier/fp-intrinsics.ll
new file mode 100644
index 00000000000..0a308115cc3
--- /dev/null
+++ b/llvm/test/Verifier/fp-intrinsics.ll
@@ -0,0 +1,43 @@
+; RUN: opt -verify -S < %s 2>&1 | FileCheck --check-prefix=CHECK1 %s
+; RUN: sed -e s/.T2:// %s | not opt -verify -disable-output 2>&1 | FileCheck --check-prefix=CHECK2 %s
+; RUN: sed -e s/.T3:// %s | not opt -verify -disable-output 2>&1 | FileCheck --check-prefix=CHECK3 %s
+
+; Common declaration used for all runs.
+declare double @llvm.experimental.constrained.fadd.f64(double, double, metadata, metadata)
+
+; Test that the verifier accepts legal code, and that the correct attributes are
+; attached to the FP intrinsic.
+; CHECK1: declare double @llvm.experimental.constrained.fadd.f64(double, double, metadata, metadata) #[[ATTR:[0-9]+]]
+; CHECK1: attributes #[[ATTR]] = { inaccessiblememonly nounwind }
+; Note: FP exceptions aren't usually caught through normal unwind mechanisms,
+;       but we may want to revisit this for asynchronous exception handling.
+define double @f1(double %a, double %b) {
+entry:
+  %fadd = call double @llvm.experimental.constrained.fadd.f64(
+                                               double %a, double %b,
+                                               metadata !"round.dynamic",
+                                               metadata !"fpexcept.strict")
+  ret double %fadd
+}
+
+; Test an illegal value for the rounding mode argument.
+; CHECK2: invalid rounding mode argument
+;T2: define double @f2(double %a, double %b) {
+;T2: entry:
+;T2:   %fadd = call double @llvm.experimental.constrained.fadd.f64(
+;T2:                                           double %a, double %b,
+;T2:                                           metadata !"round.dynomite",
+;T2:                                           metadata !"fpexcept.strict")
+;T2:   ret double %fadd
+;T2: }
+
+; Test an illegal value for the exception behavior argument.
+; CHECK3: invalid exception behavior argument
+;T3: define double @f2(double %a, double %b) {
+;T3: entry:
+;T3:   %fadd = call double @llvm.experimental.constrained.fadd.f64(
+;T3:                                         double %a, double %b,
+;T3:                                         metadata !"round.dynamic",
+;T3:                                         metadata !"fpexcept.restrict")
+;T3:   ret double %fadd
+;T3: }