Index: lib/Transforms/InstCombine/InstCombineSelect.cpp
===================================================================
--- lib/Transforms/InstCombine/InstCombineSelect.cpp
+++ lib/Transforms/InstCombine/InstCombineSelect.cpp
@@ -58,22 +58,32 @@
 /// constant of a binop.
 static Instruction *foldSelectBinOpIdentity(SelectInst &Sel) {
   // The select condition must be an equality compare with a constant operand.
-  // TODO: Support FP compares.
   Value *X;
   Constant *C;
   CmpInst::Predicate Pred;
-  if (!match(Sel.getCondition(), m_ICmp(Pred, m_Value(X), m_Constant(C))) ||
-      !ICmpInst::isEquality(Pred))
+  if (!match(Sel.getCondition(), m_Cmp(Pred, m_Value(X), m_Constant(C))))
+    return nullptr;
+
+  bool IsEq;
+  if (ICmpInst::isEquality(Pred))
+    IsEq = Pred == ICmpInst::ICMP_EQ;
+  else if (Pred == FCmpInst::FCMP_OEQ)
+    IsEq = true;
+  else if (Pred == FCmpInst::FCMP_ONE)
+    IsEq = false;
+  else
     return nullptr;
 
   // A select operand must be a binop, and the compare constant must be the
   // identity constant for that binop.
-  bool IsEq = Pred == ICmpInst::ICMP_EQ;
   BinaryOperator *BO;
   if (!match(Sel.getOperand(IsEq ? 1 : 2), m_BinOp(BO)) ||
       ConstantExpr::getBinOpIdentity(BO->getOpcode(), BO->getType(), true) != C)
     return nullptr;
 
+  // Check for signed zeros
+  if (isa<FPMathOperator>(BO) && !BO->hasNoSignedZeros())
+    return nullptr;
   // Last, match the compare variable operand with a binop operand.
   Value *Y;
   if (!BO->isCommutative() && !match(BO, m_BinOp(m_Value(Y), m_Specific(X))))
Index: test/Transforms/InstCombine/select-binop-cmp.ll
===================================================================
--- test/Transforms/InstCombine/select-binop-cmp.ll
+++ test/Transforms/InstCombine/select-binop-cmp.ll
@@ -143,51 +143,23 @@
 define float @select_fadd_fcmp(float %x, float %y, float %z) {
 ; CHECK-LABEL: @select_fadd_fcmp(
 ; CHECK-NEXT:    [[A:%.*]] = fcmp oeq float [[X:%.*]], -0.000000e+00
-; CHECK-NEXT:    [[B:%.*]] = fadd float [[X]], [[Z:%.*]]
-; CHECK-NEXT:    [[C:%.*]] = select i1 [[A]], float [[B]], float [[Y:%.*]]
+; CHECK-NEXT:    [[C:%.*]] = select i1 [[A]], float [[Z:%.*]], float [[Y:%.*]]
 ; CHECK-NEXT:    ret float [[C]]
 ;
   %A = fcmp oeq float %x, -0.0
-  %B = fadd float %x, %z
+  %B = fadd nsz float %x, %z
   %C = select i1 %A, float %B, float %y
   ret float %C
 }
 
 define float @select_fadd_fcmp_2(float %x, float %y, float %z) {
 ; CHECK-LABEL: @select_fadd_fcmp_2(
-; CHECK-NEXT:    [[A:%.*]] = fcmp ueq float [[X:%.*]], -0.000000e+00
-; CHECK-NEXT:    [[B:%.*]] = fadd float [[X]], [[Z:%.*]]
-; CHECK-NEXT:    [[C:%.*]] = select i1 [[A]], float [[B]], float [[Y:%.*]]
-; CHECK-NEXT:    ret float [[C]]
-;
-  %A = fcmp ueq float %x, -0.0
-  %B = fadd float %x, %z
-  %C = select i1 %A, float %B, float %y
-  ret float %C
-}
-
-define float @select_fadd_fcmp_3(float %x, float %y, float %z) {
-; CHECK-LABEL: @select_fadd_fcmp_3(
 ; CHECK-NEXT:    [[A:%.*]] = fcmp one float [[X:%.*]], -0.000000e+00
-; CHECK-NEXT:    [[B:%.*]] = fadd float [[Z:%.*]], [[X]]
-; CHECK-NEXT:    [[C:%.*]] = select i1 [[A]], float [[Y:%.*]], float [[B]]
+; CHECK-NEXT:    [[C:%.*]] = select i1 [[A]], float [[Y:%.*]], float [[Z:%.*]]
 ; CHECK-NEXT:    ret float [[C]]
 ;
   %A = fcmp one float %x, -0.0
-  %B = fadd float %z, %x
-  %C = select i1 %A, float %y, float %B
-  ret float %C
-}
-
-define float @select_fadd_fcmp_4(float %x, float %y, float %z) {
-; CHECK-LABEL: @select_fadd_fcmp_4(
-; CHECK-NEXT:    [[A:%.*]] = fcmp une float [[X:%.*]], -0.000000e+00
-; CHECK-NEXT:    [[B:%.*]] = fadd float [[Z:%.*]], [[X]]
-; CHECK-NEXT:    [[C:%.*]] = select i1 [[A]], float [[Y:%.*]], float [[B]]
-; CHECK-NEXT:    ret float [[C]]
-;
-  %A = fcmp une float %x, -0.0
-  %B = fadd float %z, %x
+  %B = fadd nsz float %z, %x
   %C = select i1 %A, float %y, float %B
   ret float %C
 }
@@ -195,12 +167,11 @@
 define float @select_fmul_fcmp(float %x, float %y, float %z) {
 ; CHECK-LABEL: @select_fmul_fcmp(
 ; CHECK-NEXT:    [[A:%.*]] = fcmp oeq float [[X:%.*]], 1.000000e+00
-; CHECK-NEXT:    [[B:%.*]] = fmul float [[X]], [[Z:%.*]]
-; CHECK-NEXT:    [[C:%.*]] = select i1 [[A]], float [[B]], float [[Y:%.*]]
+; CHECK-NEXT:    [[C:%.*]] = select i1 [[A]], float [[Z:%.*]], float [[Y:%.*]]
 ; CHECK-NEXT:    ret float [[C]]
 ;
   %A = fcmp oeq float %x, 1.0
-  %B = fmul float %x, %z
+  %B = fmul nsz float %x, %z
   %C = select i1 %A, float %B, float %y
   ret float %C
 }
@@ -208,12 +179,11 @@
 define float @select_fsub_fcmp(float %x, float %y, float %z) {
 ; CHECK-LABEL: @select_fsub_fcmp(
 ; CHECK-NEXT:    [[A:%.*]] = fcmp oeq float [[X:%.*]], 0.000000e+00
-; CHECK-NEXT:    [[B:%.*]] = fsub float [[Z:%.*]], [[X]]
-; CHECK-NEXT:    [[C:%.*]] = select i1 [[A]], float [[B]], float [[Y:%.*]]
+; CHECK-NEXT:    [[C:%.*]] = select i1 [[A]], float [[Z:%.*]], float [[Y:%.*]]
 ; CHECK-NEXT:    ret float [[C]]
 ;
   %A = fcmp oeq float %x, 0.0
-  %B = fsub float %z, %x
+  %B = fsub nsz float %z, %x
   %C = select i1 %A, float %B, float %y
   ret float %C
 }
@@ -221,12 +191,11 @@
 define float @select_fdiv_fcmp(float %x, float %y, float %z) {
 ; CHECK-LABEL: @select_fdiv_fcmp(
 ; CHECK-NEXT:    [[A:%.*]] = fcmp oeq float [[X:%.*]], 1.000000e+00
-; CHECK-NEXT:    [[B:%.*]] = fdiv float [[Z:%.*]], [[X]]
-; CHECK-NEXT:    [[C:%.*]] = select i1 [[A]], float [[B]], float [[Y:%.*]]
+; CHECK-NEXT:    [[C:%.*]] = select i1 [[A]], float [[Z:%.*]], float [[Y:%.*]]
 ; CHECK-NEXT:    ret float [[C]]
 ;
   %A = fcmp oeq float %x, 1.0
-  %B = fdiv float %z, %x
+  %B = fdiv nsz float %z, %x
   %C = select i1 %A, float %B, float %y
   ret float %C
 }
@@ -510,12 +479,12 @@
 define float @select_fadd_fcmp_bad(float %x, float %y, float %z) {
 ; CHECK-LABEL: @select_fadd_fcmp_bad(
 ; CHECK-NEXT:    [[A:%.*]] = fcmp oeq float [[X:%.*]], -1.000000e+00
-; CHECK-NEXT:    [[B:%.*]] = fadd float [[X]], [[Z:%.*]]
+; CHECK-NEXT:    [[B:%.*]] = fadd nsz float [[X]], [[Z:%.*]]
 ; CHECK-NEXT:    [[C:%.*]] = select i1 [[A]], float [[B]], float [[Y:%.*]]
 ; CHECK-NEXT:    ret float [[C]]
 ;
   %A = fcmp oeq float %x, -1.0
-  %B = fadd float %x, %z
+  %B = fadd nsz float %x, %z
   %C = select i1 %A, float %B, float %y
   ret float %C
 }
@@ -559,14 +528,65 @@
   ret float %C
 }
 
+define float @select_fadd_fcmp_bad_5(float %x, float %y, float %z) {
+; CHECK-LABEL: @select_fadd_fcmp_bad_5(
+; CHECK-NEXT:    [[A:%.*]] = fcmp one float [[X:%.*]], -0.000000e+00
+; CHECK-NEXT:    [[C:%.*]] = select i1 [[A]], float [[Y:%.*]], float [[Z:%.*]]
+; CHECK-NEXT:    ret float [[C]]
+;
+  %A = fcmp one float %x, -0.0
+  %B = fadd nsz float %z, %x
+  %C = select i1 %A, float %y, float %B
+  ret float %C
+}
+
+define float @select_fadd_fcmp_bad_6(float %x, float %y, float %z) {
+; CHECK-LABEL: @select_fadd_fcmp_bad_6(
+; CHECK-NEXT:    [[A:%.*]] = fcmp une float [[X:%.*]], -0.000000e+00
+; CHECK-NEXT:    [[B:%.*]] = fadd nsz float [[Z:%.*]], [[X]]
+; CHECK-NEXT:    [[C:%.*]] = select i1 [[A]], float [[Y:%.*]], float [[B]]
+; CHECK-NEXT:    ret float [[C]]
+;
+  %A = fcmp une float %x, -0.0
+  %B = fadd nsz float %z, %x
+  %C = select i1 %A, float %y, float %B
+  ret float %C
+}
+
+define float @select_fadd_fcmp_bad_7(float %x, float %y, float %z) {
+; CHECK-LABEL: @select_fadd_fcmp_bad_7(
+; CHECK-NEXT:    [[A:%.*]] = fcmp oeq float [[X:%.*]], -0.000000e+00
+; CHECK-NEXT:    [[B:%.*]] = fadd float [[X]], [[Z:%.*]]
+; CHECK-NEXT:    [[C:%.*]] = select i1 [[A]], float [[B]], float [[Y:%.*]]
+; CHECK-NEXT:    ret float [[C]]
+;
+  %A = fcmp oeq float %x, -0.0
+  %B = fadd float %x, %z
+  %C = select i1 %A, float %B, float %y
+  ret float %C
+}
+
 define float @select_fmul_fcmp_bad(float %x, float %y, float %z) {
 ; CHECK-LABEL: @select_fmul_fcmp_bad(
 ; CHECK-NEXT:    [[A:%.*]] = fcmp oeq float [[X:%.*]], 3.000000e+00
-; CHECK-NEXT:    [[B:%.*]] = fmul float [[X]], [[Z:%.*]]
+; CHECK-NEXT:    [[B:%.*]] = fmul nsz float [[X]], [[Z:%.*]]
 ; CHECK-NEXT:    [[C:%.*]] = select i1 [[A]], float [[B]], float [[Y:%.*]]
 ; CHECK-NEXT:    ret float [[C]]
 ;
   %A = fcmp oeq float %x, 3.0
+  %B = fmul nsz float %x, %z
+  %C = select i1 %A, float %B, float %y
+  ret float %C
+}
+
+define float @select_fmul_fcmp_bad_2(float %x, float %y, float %z) {
+; CHECK-LABEL: @select_fmul_fcmp_bad_2(
+; CHECK-NEXT:    [[A:%.*]] = fcmp oeq float [[X:%.*]], 1.000000e+00
+; CHECK-NEXT:    [[B:%.*]] = fmul float [[X]], [[Z:%.*]]
+; CHECK-NEXT:    [[C:%.*]] = select i1 [[A]], float [[B]], float [[Y:%.*]]
+; CHECK-NEXT:    ret float [[C]]
+;
+  %A = fcmp oeq float %x, 1.0
   %B = fmul float %x, %z
   %C = select i1 %A, float %B, float %y
   ret float %C
@@ -585,32 +605,71 @@
   ret float %C
 }
 
+define float @select_fmul_icmp_bad_2(float %x, float %y, float %z, i32 %k) {
+; CHECK-LABEL: @select_fmul_icmp_bad_2(
+; CHECK-NEXT:    [[A:%.*]] = icmp eq i32 [[K:%.*]], 0
+; CHECK-NEXT:    [[B:%.*]] = fmul nsz float [[X:%.*]], [[Z:%.*]]
+; CHECK-NEXT:    [[C:%.*]] = select i1 [[A]], float [[B]], float [[Y:%.*]]
+; CHECK-NEXT:    ret float [[C]]
+;
+  %A = icmp eq i32 %k, 0
+  %B = fmul nsz float %x, %z
+  %C = select i1 %A, float %B, float %y
+  ret float %C
+}
+
 define float @select_fdiv_fcmp_bad(float %x, float %y, float %z) {
 ; CHECK-LABEL: @select_fdiv_fcmp_bad(
-; CHECK-NEXT:    [[A:%.*]] = fcmp oeq float [[X:%.*]], 3.000000e+00
+; CHECK-NEXT:    [[A:%.*]] = fcmp oeq float [[X:%.*]], 1.000000e+00
 ; CHECK-NEXT:    [[B:%.*]] = fdiv float [[X]], [[Z:%.*]]
 ; CHECK-NEXT:    [[C:%.*]] = select i1 [[A]], float [[B]], float [[Y:%.*]]
 ; CHECK-NEXT:    ret float [[C]]
 ;
-  %A = fcmp oeq float %x, 3.0
+  %A = fcmp oeq float %x, 1.0
   %B = fdiv float %x, %z
   %C = select i1 %A, float %B, float %y
   ret float %C
 }
 
+define float @select_fdiv_fcmp_bad_2(float %x, float %y, float %z) {
+; CHECK-LABEL: @select_fdiv_fcmp_bad_2(
+; CHECK-NEXT:    [[A:%.*]] = fcmp oeq float [[X:%.*]], 3.000000e+00
+; CHECK-NEXT:    [[B:%.*]] = fdiv nsz float [[X]], [[Z:%.*]]
+; CHECK-NEXT:    [[C:%.*]] = select i1 [[A]], float [[B]], float [[Y:%.*]]
+; CHECK-NEXT:    ret float [[C]]
+;
+  %A = fcmp oeq float %x, 3.0
+  %B = fdiv nsz float %x, %z
+  %C = select i1 %A, float %B, float %y
+  ret float %C
+}
+
 define float @select_fsub_fcmp_bad(float %x, float %y, float %z) {
 ; CHECK-LABEL: @select_fsub_fcmp_bad(
-; CHECK-NEXT:    [[A:%.*]] = fcmp oeq float [[X:%.*]], 1.000000e+00
+; CHECK-NEXT:    [[A:%.*]] = fcmp oeq float [[X:%.*]], 0.000000e+00
 ; CHECK-NEXT:    [[B:%.*]] = fsub float [[X]], [[Z:%.*]]
 ; CHECK-NEXT:    [[C:%.*]] = select i1 [[A]], float [[B]], float [[Y:%.*]]
 ; CHECK-NEXT:    ret float [[C]]
 ;
-  %A = fcmp oeq float %x, 1.0
+  %A = fcmp oeq float %x, 0.0
   %B = fsub float %x, %z
   %C = select i1 %A, float %B, float %y
   ret float %C
 }
 
+define float @select_fsub_fcmp_bad_2(float %x, float %y, float %z) {
+; CHECK-LABEL: @select_fsub_fcmp_bad_2(
+; CHECK-NEXT:    [[A:%.*]] = fcmp oeq float [[X:%.*]], 1.000000e+00
+; CHECK-NEXT:    [[B:%.*]] = fsub nsz float [[X]], [[Z:%.*]]
+; CHECK-NEXT:    [[C:%.*]] = select i1 [[A]], float [[B]], float [[Y:%.*]]
+; CHECK-NEXT:    ret float [[C]]
+;
+  %A = fcmp oeq float %x, 1.0
+  %B = fsub nsz float %x, %z
+  %C = select i1 %A, float %B, float %y
+  ret float %C
+}
+
 define i32 @select_sub_icmp_bad(i32 %x, i32 %y, i32 %z) {
 ; CHECK-LABEL: @select_sub_icmp_bad(
 ; CHECK-NEXT:    [[A:%.*]] = icmp eq i32 [[X:%.*]], 0