[PATCH] D27522: [X86] Don't allow floating-point return types when SSE[12] is disabled

[Visoiu Mistrih Francis via Phabricator via llvm-commits]

thegameg created this revision.
thegameg added reviewers: craig.topper, mkuper, hfinkel, joerg, RKSimon.
thegameg added a subscriber: llvm-commits.

The following program hits a fatal_error in the X86 backend, when the
program is compiled with -mno-sse or -mno-sse2, which is understandable
due to the calling convention:

> float f() { return 0.5f; };

since the error occurs in the backend, there are stack traces and bug
report messages that are generated.

This patch allows clang to avoid crashing and report a proper diagnostic.

No tests are included in this patch, since it was already tested in llvm's codegen test suite.


https://reviews.llvm.org/D27522

Files:
  lib/Target/X86/X86ISelLowering.cpp


Index: lib/Target/X86/X86ISelLowering.cpp
===================================================================
--- lib/Target/X86/X86ISelLowering.cpp
+++ lib/Target/X86/X86ISelLowering.cpp
@@ -44,6 +44,7 @@
 #include "llvm/IR/GlobalVariable.h"
 #include "llvm/IR/Instructions.h"
 #include "llvm/IR/Intrinsics.h"
+#include "llvm/IR/DiagnosticInfo.h"
 #include "llvm/MC/MCAsmInfo.h"
 #include "llvm/MC/MCContext.h"
 #include "llvm/MC/MCExpr.h"
@@ -69,6 +70,14 @@
              "rather than promotion."),
     cl::Hidden);
 
+namespace {
+void diagnose_fatal_error(SelectionDAG &DAG, const SDLoc &dl, const char *msg) {
+  MachineFunction &MF = DAG.getMachineFunction();
+  DAG.getContext()->diagnose(
+      DiagnosticInfoUnsupported(*MF.getFunction(), msg, dl.getDebugLoc()));
+}
+}
+
 X86TargetLowering::X86TargetLowering(const X86TargetMachine &TM,
                                      const X86Subtarget &STI)
     : TargetLowering(TM), Subtarget(STI) {
@@ -2189,15 +2198,17 @@
     // or SSE or MMX vectors.
     if ((ValVT == MVT::f32 || ValVT == MVT::f64 ||
          VA.getLocReg() == X86::XMM0 || VA.getLocReg() == X86::XMM1) &&
-          (Subtarget.is64Bit() && !Subtarget.hasSSE1())) {
-      report_fatal_error("SSE register return with SSE disabled");
+        (Subtarget.is64Bit() && !Subtarget.hasSSE1())) {
+      diagnose_fatal_error(DAG, dl, "SSE register return with SSE disabled");
+      VA.convertToReg(X86::FP0); // Set reg to FP0, avoid hitting asserts.
     }
     // Likewise we can't return F64 values with SSE1 only.  gcc does so, but
     // llvm-gcc has never done it right and no one has noticed, so this
     // should be OK for now.
-    if (ValVT == MVT::f64 &&
-        (Subtarget.is64Bit() && !Subtarget.hasSSE2()))
-      report_fatal_error("SSE2 register return with SSE2 disabled");
+    if (ValVT == MVT::f64 && (Subtarget.is64Bit() && !Subtarget.hasSSE2())) {
+      diagnose_fatal_error(DAG, dl, "SSE2 register return with SSE2 disabled");
+      VA.convertToReg(X86::FP0); // Set reg to FP0, avoid hitting asserts.
+    }
 
     // Returns in ST0/ST1 are handled specially: these are pushed as operands to
     // the RET instruction and handled by the FP Stackifier.
@@ -2477,7 +2488,8 @@
     // If this is x86-64, and we disabled SSE, we can't return FP values
     if ((CopyVT == MVT::f32 || CopyVT == MVT::f64 || CopyVT == MVT::f128) &&
         ((Is64Bit || Ins[InsIndex].Flags.isInReg()) && !Subtarget.hasSSE1())) {
-      report_fatal_error("SSE register return with SSE disabled");
+      diagnose_fatal_error(DAG, dl, "SSE register return with SSE disabled");
+      VA.convertToReg(X86::FP0); // Set reg to FP0, avoid hitting asserts.
     }
 
     // If we prefer to use the value in xmm registers, copy it out as f80 and


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