Merge pull request #10424 from JuliaLang/tk/fix10377

Carry local patch to fix #10377

deps/Makefile

@@ -515,6 +515,8 @@ ifeq ($(ARCH),x86_64)
  patch -p0 < win64-int128.llvm-3.3.patch
 endif
 endif
+else ifeq ($(LLVM_VER),3.6.0)
+ cd llvm-3.6.0 && patch -p1 < ../zerosign-llvm-3.6.0.patch
 endif
  touch -c $@
 

deps/zerosign-llvm-3.6.0.patch

@@ -0,0 +1,103 @@
+diff --git a/lib/Transforms/Scalar/GVN.cpp b/lib/Transforms/Scalar/GVN.cpp
+index 4a85780..73a1f25 100644
+--- a/lib/Transforms/Scalar/GVN.cpp
++++ b/lib/Transforms/Scalar/GVN.cpp
+@@ -2182,12 +2182,16 @@ bool GVN::propagateEquality(Value *LHS, Value *RHS,
+ // Handle the floating point versions of equality comparisons too.
+ if ((isKnownTrue && Cmp->getPredicate() == CmpInst::FCMP_OEQ) ||
+ (isKnownFalse && Cmp->getPredicate() == CmpInst::FCMP_UNE)) {
+- // Floating point -0.0 and 0.0 compare equal, so we can't
+- // propagate a constant based on that comparison.
++
++ // Floating point -0.0 and 0.0 compare equal, so we can only
++ // propagate values if we know that we have a constant and that
++ // its value is non-zero.
++ 
+ // FIXME: We should do this optimization if 'no signed zeros' is
+ // applicable via an instruction-level fast-math-flag or some other
+ // indicator that relaxed FP semantics are being used.
+- if (!isa<ConstantFP>(Op1) || !cast<ConstantFP>(Op1)->isZero())
++
++ if (isa<ConstantFP>(Op1) && !cast<ConstantFP>(Op1)->isZero())
+ Worklist.push_back(std::make_pair(Op0, Op1));
+ }
+
+diff --git a/test/Transforms/GVN/edge.ll b/test/Transforms/GVN/edge.ll
+index f28a76b..0c1a3fb 100644
+--- a/test/Transforms/GVN/edge.ll
++++ b/test/Transforms/GVN/edge.ll
+@@ -59,7 +59,7 @@ bb2:
+ ret void
+ }
+
+-define double @fcmp_oeq(double %x, double %y) {
++define double @fcmp_oeq_not_zero(double %x, double %y) {
+ entry:
+ %cmp = fcmp oeq double %y, 2.0
+ br i1 %cmp, label %if, label %return
+@@ -72,11 +72,11 @@ return:
+ %retval = phi double [ %div, %if ], [ %x, %entry ]
+ ret double %retval
+
+-; CHECK-LABEL: define double @fcmp_oeq(
++; CHECK-LABEL: define double @fcmp_oeq_not_zero(
+ ; CHECK: %div = fdiv double %x, 2.0
+ }
+
+-define double @fcmp_une(double %x, double %y) {
++define double @fcmp_une_not_zero(double %x, double %y) {
+ entry:
+ %cmp = fcmp une double %y, 2.0
+ br i1 %cmp, label %return, label %else
+@@ -89,7 +89,7 @@ return:
+ %retval = phi double [ %div, %else ], [ %x, %entry ]
+ ret double %retval
+
+-; CHECK-LABEL: define double @fcmp_une(
++; CHECK-LABEL: define double @fcmp_une_not_zero(
+ ; CHECK: %div = fdiv double %x, 2.0
+ }
+
+@@ -129,3 +129,42 @@ return:
+ ; CHECK-LABEL: define double @fcmp_une_zero(
+ ; CHECK: %div = fdiv double %x, %y
+ }
++
++; We also cannot propagate a value if it's not a constant.
++; This is because the value could be 0.0 or -0.0.
++
++define double @fcmp_oeq_maybe_zero(double %x, double %y, double %z1, double %z2) {
++entry:
++ %z = fadd double %z1, %z2
++ %cmp = fcmp oeq double %y, %z
++ br i1 %cmp, label %if, label %return
++
++if:
++ %div = fdiv double %x, %z
++ br label %return
++
++return:
++ %retval = phi double [ %div, %if ], [ %x, %entry ]
++ ret double %retval
++
++; CHECK-LABEL: define double @fcmp_oeq_maybe_zero(
++; CHECK: %div = fdiv double %x, %z
++}
++
++define double @fcmp_une_maybe_zero(double %x, double %y, double %z1, double %z2) {
++entry:
++ %z = fadd double %z1, %z2
++ %cmp = fcmp une double %y, %z
++ br i1 %cmp, label %return, label %else
++
++else:
++ %div = fdiv double %x, %z
++ br label %return
++
++return:
++ %retval = phi double [ %div, %else ], [ %x, %entry ]
++ ret double %retval
++
++; CHECK-LABEL: define double @fcmp_une_maybe_zero(
++; CHECK: %div = fdiv double %x, %z
++}