[PATCH] D15240: X86: Don't emit SAHF/LAHF for 64-bit targets unless explicitly supported

[JF Bastien via llvm-commits]

jfb accepted this revision.
jfb added a comment.
This revision is now accepted and ready to land.

Sorry, a few more comments. lgtm otherwise.


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Comment at: lib/Target/X86/X86.td:564
@@ -549,3 +563,3 @@
                                FeatureCMPXCHG16B, FeatureLZCNT, FeaturePOPCNT,
                                FeatureSlowBTMem, FeatureSlowSHLD]>;
 
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Looks like the above two should also have lahf/sahf.

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Comment at: lib/Target/X86/X86InstrInfo.cpp:4398
@@ +4397,3 @@
+    if (!Subtarget.hasLAHFSAHF()) {
+      // Moving EFLAGS to / from another register requires a push and a pop.
+      // Notice that we have to adjust the stack if we don't want to clobber the
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IIUC you can `assert(is64);` here?


http://reviews.llvm.org/D15240