From: Chris Lattner <sabre@nondot.org>
Date: Wed, 18 Mar 2009 00:43:52 +0000 (+0000)
Subject: Disable the "call to immediate" optimization on x86-64.  It is
X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=ff81ebf7586fa7992353ed44a8c9d564130fb734;p=oota-llvm.git

Disable the "call to immediate" optimization on x86-64.  It is
not safe in general because the immediate could be an arbitrary
value that does not fit in a 32-bit pcrel displacement.
Conservatively fall back to loading the value into a register
and calling through it.

We still do the optzn on X86-32.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@67142 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Target/X86/X86Instr64bit.td b/lib/Target/X86/X86Instr64bit.td
index a6c0800c80c..73e1f9814b0 100644
--- a/lib/Target/X86/X86Instr64bit.td
+++ b/lib/Target/X86/X86Instr64bit.td
@@ -109,9 +109,13 @@ let isCall = 1 in
               XMM0, XMM1, XMM2, XMM3, XMM4, XMM5, XMM6, XMM7,
               XMM8, XMM9, XMM10, XMM11, XMM12, XMM13, XMM14, XMM15, EFLAGS],
       Uses = [RSP] in {
+      
+    // NOTE: this pattern doesn't match "X86call imm", because we do not know
+    // that the offset between an arbitrary immediate and the call will fit in
+    // the 32-bit pcrel field that we have.
     def CALL64pcrel32 : I<0xE8, RawFrm,
                           (outs), (ins i64i32imm:$dst, variable_ops),
-                          "call\t${dst:call}", [(X86call imm:$dst)]>,
+                          "call\t${dst:call}", []>,
                         Requires<[In64BitMode]>;
     def CALL64r       : I<0xFF, MRM2r, (outs), (ins GR64:$dst, variable_ops),
                           "call\t{*}$dst", [(X86call GR64:$dst)]>;
diff --git a/test/CodeGen/X86/call-imm.ll b/test/CodeGen/X86/call-imm.ll
index b99149b687f..8233d8698ab 100644
--- a/test/CodeGen/X86/call-imm.ll
+++ b/test/CodeGen/X86/call-imm.ll
@@ -1,6 +1,10 @@
-; RUN: llvm-as < %s | llc -march=x86    | grep call | not grep {*}
-; RUN: llvm-as < %s | llc -march=x86    | grep call | grep 12345678
-; RUN: llvm-as < %s | llc -march=x86-64 | grep call | grep 12345678
+; RUN: llvm-as < %s | llc -march=x86    | grep {call.*12345678}
+
+; Call to immediate is not safe on x86-64 unless we *know* that the
+; call will be within 32-bits pcrel from the dest immediate.
+
+; RUN: llvm-as < %s | llc -march=x86-64 | grep {call.*\*%rax}
+
 ; PR3666
 ; PR3773