Subzero: Use a "deterministic" random shuffle for register allocation.

src/IceRNG.h

@@ -53,6 +53,15 @@ private:
   RandomNumberGenerator &RNG;
 };
 
+// RandomShuffle is an implementation of std::random_shuffle() that
+// doesn't change across stdlib implementations.  Adapted from a
+// sample implementation at cppreference.com.
+template <class RandomIt, class RandomFunc>
+void RandomShuffle(RandomIt First, RandomIt Last, RandomFunc &&RNG) {
+  for (auto i = Last - First - 1; i > 0; --i)
+    std::swap(First[i], First[RNG(i + 1)]);
+}
+
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICERNG_H

src/IceTargetLoweringX8632.cpp

@@ -4621,7 +4621,7 @@ void TargetX8632::makeRandomRegisterPermutation(
   for (auto I : EquivalenceClasses) {
     const RegisterList &List = I.second;
     RegisterList Shuffled(List);
-    std::random_shuffle(Shuffled.begin(), Shuffled.end(), RNG);
+    RandomShuffle(Shuffled.begin(), Shuffled.end(), RNG);
     for (size_t SI = 0, SE = Shuffled.size(); SI < SE; ++SI) {
       Permutation[List[SI]] = Shuffled[SI];
       ++NumShuffled;

tests_lit/llvm2ice_tests/randomize-regalloc.ll

@@ -26,11 +26,11 @@ entry:
 ; OPTM1_1-NEXT: movups  XMMWORD PTR [esp+0x20],xmm0
 ; OPTM1_1-NEXT: movups  XMMWORD PTR [esp+0x10],xmm1
 ; OPTM1_1-NEXT: movups  xmm0,XMMWORD PTR [esp+0x20]
-; OPTM1_1-NEXT: pshufd  xmm7,XMMWORD PTR [esp+0x20],0x31
-; OPTM1_1-NEXT: pshufd  xmm4,XMMWORD PTR [esp+0x10],0x31
+; OPTM1_1-NEXT: pshufd  xmm1,XMMWORD PTR [esp+0x20],0x31
+; OPTM1_1-NEXT: pshufd  xmm2,XMMWORD PTR [esp+0x10],0x31
 ; OPTM1_1-NEXT: pmuludq xmm0,XMMWORD PTR [esp+0x10]
-; OPTM1_1-NEXT: pmuludq xmm7,xmm4
-; OPTM1_1-NEXT: shufps  xmm0,xmm7,0x88
+; OPTM1_1-NEXT: pmuludq xmm1,xmm2
+; OPTM1_1-NEXT: shufps  xmm0,xmm1,0x88
 ; OPTM1_1-NEXT: pshufd  xmm0,xmm0,0xd8
 ; OPTM1_1-NEXT: movups  XMMWORD PTR [esp],xmm0
 ; OPTM1_1-NEXT: movups  xmm0,XMMWORD PTR [esp]
@@ -38,14 +38,14 @@ entry:
 ; OPTM1_1-NEXT: ret
 
 ; CHECK_1-LABEL: mul_v4i32
-; CHECK_1: movups  xmm6,xmm0
+; CHECK_1: movups  xmm5,xmm0
 ; CHECK_1-NEXT: pshufd  xmm0,xmm0,0x31
-; CHECK_1-NEXT: pshufd  xmm5,xmm1,0x31
-; CHECK_1-NEXT: pmuludq xmm6,xmm1
-; CHECK_1-NEXT: pmuludq xmm0,xmm5
-; CHECK_1-NEXT: shufps  xmm6,xmm0,0x88
-; CHECK_1-NEXT: pshufd  xmm6,xmm6,0xd8
-; CHECK_1-NEXT: movups  xmm0,xmm6
+; CHECK_1-NEXT: pshufd  xmm3,xmm1,0x31
+; CHECK_1-NEXT: pmuludq xmm5,xmm1
+; CHECK_1-NEXT: pmuludq xmm0,xmm3
+; CHECK_1-NEXT: shufps  xmm5,xmm0,0x88
+; CHECK_1-NEXT: pshufd  xmm5,xmm5,0xd8
+; CHECK_1-NEXT: movups  xmm0,xmm5
 ; CHECK_1-NEXT: ret
 
 ; OPTM1_123-LABEL: mul_v4i32
@@ -53,11 +53,11 @@ entry:
 ; OPTM1_123-NEXT: movups  XMMWORD PTR [esp+0x20],xmm0
 ; OPTM1_123-NEXT: movups  XMMWORD PTR [esp+0x10],xmm1
 ; OPTM1_123-NEXT: movups  xmm0,XMMWORD PTR [esp+0x20]
-; OPTM1_123-NEXT: pshufd  xmm2,XMMWORD PTR [esp+0x20],0x31
+; OPTM1_123-NEXT: pshufd  xmm1,XMMWORD PTR [esp+0x20],0x31
 ; OPTM1_123-NEXT: pshufd  xmm6,XMMWORD PTR [esp+0x10],0x31
 ; OPTM1_123-NEXT: pmuludq xmm0,XMMWORD PTR [esp+0x10]
-; OPTM1_123-NEXT: pmuludq xmm2,xmm6
-; OPTM1_123-NEXT: shufps  xmm0,xmm2,0x88
+; OPTM1_123-NEXT: pmuludq xmm1,xmm6
+; OPTM1_123-NEXT: shufps  xmm0,xmm1,0x88
 ; OPTM1_123-NEXT: pshufd  xmm0,xmm0,0xd8
 ; OPTM1_123-NEXT: movups  XMMWORD PTR [esp],xmm0
 ; OPTM1_123-NEXT: movups  xmm0,XMMWORD PTR [esp]
@@ -65,14 +65,14 @@ entry:
 ; OPTM1_123-NEXT: ret
 
 ; CHECK_123-LABEL: mul_v4i32
-; CHECK_123: movups  xmm3,xmm0
+; CHECK_123: movups  xmm4,xmm0
 ; CHECK_123-NEXT: pshufd  xmm0,xmm0,0x31
-; CHECK_123-NEXT: pshufd  xmm7,xmm1,0x31
-; CHECK_123-NEXT: pmuludq xmm3,xmm1
-; CHECK_123-NEXT: pmuludq xmm0,xmm7
-; CHECK_123-NEXT: shufps  xmm3,xmm0,0x88
-; CHECK_123-NEXT: pshufd  xmm3,xmm3,0xd8
-; CHECK_123-NEXT: movups  xmm0,xmm3
+; CHECK_123-NEXT: pshufd  xmm2,xmm1,0x31
+; CHECK_123-NEXT: pmuludq xmm4,xmm1
+; CHECK_123-NEXT: pmuludq xmm0,xmm2
+; CHECK_123-NEXT: shufps  xmm4,xmm0,0x88
+; CHECK_123-NEXT: pshufd  xmm4,xmm4,0xd8
+; CHECK_123-NEXT: movups  xmm0,xmm4
 ; CHECK_123-NEXT: ret
 }
 

unittest/IceELFSectionTest.cpp

@@ -90,8 +90,11 @@ TEST(IceELFSectionTest, StringTableBuilderPermSeveral) {
   Strings.push_back(".shstrtab");
   Strings.push_back("_start");
   const SizeT NumTests = 128;
+  const uint64_t RandomSeed = 12345; // arbitrary value for now
+  RandomNumberGenerator R(RandomSeed);
+  RandomNumberGeneratorWrapper RNG(R);
   for (SizeT i = 0; i < NumTests; ++i) {
-    std::random_shuffle(Strings.begin(), Strings.end());
+    RandomShuffle(Strings.begin(), Strings.end(), RNG);
     ELFStringTableSection Strtab(".strtab", SHT_STRTAB, 0, 1, 0);
     for (auto &S : Strings) {
       Strtab.add(S);