[X86] Fix register class for assembly constraints to ST(7). NFCI.
Modify getRegForInlineAsmConstraint to return special singleton
register class when a constraint references ST(7) not RFP80 for which
ST(7) is not a member.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@351206 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 5404c4c..de11f09 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -42477,14 +42477,17 @@
if (!Res.second) {
// Map st(0) -> st(7) -> ST0
if (Constraint.size() == 7 && Constraint[0] == '{' &&
- tolower(Constraint[1]) == 's' &&
- tolower(Constraint[2]) == 't' &&
+ tolower(Constraint[1]) == 's' && tolower(Constraint[2]) == 't' &&
Constraint[3] == '(' &&
(Constraint[4] >= '0' && Constraint[4] <= '7') &&
- Constraint[5] == ')' &&
- Constraint[6] == '}')
+ Constraint[5] == ')' && Constraint[6] == '}') {
+ // st(7) is not allocatable and thus not a member of RFP80. Return
+ // singleton class in cases where we have a reference to it.
+ if (Constraint[4] == '7')
+ return std::make_pair(X86::FP7, &X86::RFP80_7RegClass);
return std::make_pair(X86::FP0 + Constraint[4] - '0',
&X86::RFP80RegClass);
+ }
// GCC allows "st(0)" to be called just plain "st".
if (StringRef("{st}").equals_lower(Constraint))
diff --git a/lib/Target/X86/X86RegisterInfo.td b/lib/Target/X86/X86RegisterInfo.td
index 0c1b05f..aa20273 100644
--- a/lib/Target/X86/X86RegisterInfo.td
+++ b/lib/Target/X86/X86RegisterInfo.td
@@ -522,10 +522,16 @@
// faster on common hardware. In reality, this should be controlled by a
// command line option or something.
+
def RFP32 : RegisterClass<"X86",[f32], 32, (sequence "FP%u", 0, 6)>;
def RFP64 : RegisterClass<"X86",[f64], 32, (add RFP32)>;
def RFP80 : RegisterClass<"X86",[f80], 32, (add RFP32)>;
+// st(7) may be is not allocatable.
+def RFP80_7 : RegisterClass<"X86",[f80], 32, (add FP7)> {
+ let isAllocatable = 0;
+}
+
// Floating point stack registers (these are not allocatable by the
// register allocator - the floating point stackifier is responsible
// for transforming FPn allocations to STn registers)
