From: Benjamin Kramer <benny.kra@googlemail.com>
Date: Fri, 2 Jun 2017 10:50:22 +0000 (+0000)
Subject: [X86] Don't fold into memory operands into insertps in the generated folding tables.
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=f4cc8004bc18fe8bcc4f5cc20797671f4ec56202;p=llvm

[X86] Don't fold into memory operands into insertps in the generated folding tables.

insertps behaves differently, the register form selects from an input
register based on the immediate operand while the memory form just loads
the given address. We have custom code to change the immediate in cases
where that's legal, so completely remove insertps from the generated
tables.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@304540 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/test/CodeGen/X86/stack-folding-fp-avx1.ll b/test/CodeGen/X86/stack-folding-fp-avx1.ll
index a00d47bb13e..f937d484ce0 100644
--- a/test/CodeGen/X86/stack-folding-fp-avx1.ll
+++ b/test/CodeGen/X86/stack-folding-fp-avx1.ll
@@ -1926,5 +1926,19 @@ define <8 x float> @stack_fold_xorps_ymm(<8 x float> %a0, <8 x float> %a1) {
   ret <8 x float> %6
 }
 
+define <4 x float> @stack_nofold_insertps(<8 x float> %a0, <8 x float> %a1) {
+; Cannot fold this without changing the immediate.
+; CHECK-LABEL: stack_nofold_insertps
+; CHECK:       32-byte Spill
+; CHECK:       nop
+; CHECK:       32-byte Reload
+; CHECK:       vinsertps $179, {{%xmm., %xmm., %xmm.}}
+  %1 = tail call <2 x i64> asm sideeffect "nop", "=x,~{xmm2},~{xmm3},~{xmm4},~{xmm5},~{xmm6},~{xmm7},~{xmm8},~{xmm9},~{xmm10},~{xmm11},~{xmm12},~{xmm13},~{xmm14},~{xmm15},~{flags}"()
+  %v0 = shufflevector <8 x float> %a0, <8 x float> undef, <4 x i32> <i32 0, i32 1, i32 2, i32 3>
+  %v1 = shufflevector <8 x float> %a1, <8 x float> undef, <4 x i32> <i32 0, i32 1, i32 2, i32 3>
+  %res = call <4 x float> @llvm.x86.sse41.insertps(<4 x float> %v0, <4 x float> %v1, i8 179)
+  ret <4 x float> %res
+}
+
 attributes #0 = { "unsafe-fp-math"="false" }
 attributes #1 = { "unsafe-fp-math"="true" }
diff --git a/utils/TableGen/X86FoldTablesEmitter.cpp b/utils/TableGen/X86FoldTablesEmitter.cpp
index b89cee2ce4b..34f5fbc6ea3 100644
--- a/utils/TableGen/X86FoldTablesEmitter.cpp
+++ b/utils/TableGen/X86FoldTablesEmitter.cpp
@@ -101,6 +101,11 @@ const char *const NoFoldSet[] = {
     "BTS16rr", "BTS32rr", "BTS64rr",
     "BTS16mr", "BTS32mr", "BTS64mr",
 
+    // insertps cannot be folded without adjusting the immediate. There's custom
+    // code to handle it in X86InstrInfo.cpp, ignore it here.
+    "INSERTPSrr", "INSERTPSrm",
+    "VINSERTPSrr", "VINSERTPSrm", "VINSERTPSZrr", "VINSERTPSZrm",
+
     // Memory folding is enabled only when optimizing for size by DAG
     // patterns only. (issue detailed in D28744 review)
     "VCVTSS2SDrm",            "VCVTSS2SDrr",