Fix Linux x86 break (#14461)

4 files changed, 35 insertions, 8 deletions

diff --git a/src/vm/i386/cgenx86.cpp b/src/vm/i386/cgenx86.cpp
index c91a716137..19d7bbeea3 100644
--- a/src/vm/i386/cgenx86.cpp
+++ b/src/vm/i386/cgenx86.cpp
@@ -1076,7 +1076,7 @@ Stub *GenerateInitPInvokeFrameHelper()
     unsigned negSpace = FrameInfo.offsetOfFrameVptr;
 
     // mov esi, GetThread()
-    psl->X86EmitCurrentThreadFetch(kESI);
+    psl->X86EmitCurrentThreadFetch(kESI, (1 << kEDI) | (1 << kEBX) | (1 << kECX) | (1 << kEDX));
 
     // mov [edi + FrameInfo.offsetOfGSCookie], GetProcessGSCookie()
     psl->X86EmitOffsetModRM(0xc7, (X86Reg)0x0, kEDI, FrameInfo.offsetOfGSCookie - negSpace);
diff --git a/src/vm/i386/jitinterfacex86.cpp b/src/vm/i386/jitinterfacex86.cpp
index 1b470c9533..3994c2e216 100644
--- a/src/vm/i386/jitinterfacex86.cpp
+++ b/src/vm/i386/jitinterfacex86.cpp
@@ -539,7 +539,7 @@ void JIT_TrialAlloc::EmitCore(CPUSTUBLINKER *psl, CodeLabel *noLock, CodeLabel *
                  && "EAX should contain size for allocation and it doesnt!!!");
 
         // Fetch current thread into EDX, preserving EAX and ECX
-        psl->X86EmitCurrentThreadFetch(kEDX);
+        psl->X86EmitCurrentThreadFetch(kEDX, (1 << kEAX) | (1 << kECX));
 
         // Try the allocation.
 
diff --git a/src/vm/i386/stublinkerx86.cpp b/src/vm/i386/stublinkerx86.cpp
index 3b376be26d..e07b6e1c37 100644
--- a/src/vm/i386/stublinkerx86.cpp
+++ b/src/vm/i386/stublinkerx86.cpp
@@ -2360,17 +2360,43 @@ void StubLinkerCPU::EmitJITHelperLoggingThunk(PCODE pJitHelper, LPVOID helperFun
 }
 #endif // _DEBUG && !FEATURE_PAL
 
-#if !defined(FEATURE_STUBS_AS_IL)
-VOID StubLinkerCPU::X86EmitCurrentThreadFetch(X86Reg dstreg)
+VOID StubLinkerCPU::X86EmitCurrentThreadFetch(X86Reg dstreg, unsigned preservedRegSet)
 {
     CONTRACTL
     {
         STANDARD_VM_CHECK;
 
+        // It doesn't make sense to have the destination register be preserved
+        PRECONDITION((preservedRegSet & (1 << dstreg)) == 0);
         AMD64_ONLY(PRECONDITION(dstreg < 8)); // code below doesn't support high registers
     }
     CONTRACTL_END;
 
+#ifdef FEATURE_PAL
+
+    X86EmitPushRegs(preservedRegSet & ((1 << kEAX) | (1 << kEDX) | (1 << kECX)));
+
+    // call GetThread
+    X86EmitCall(NewExternalCodeLabel((LPVOID)GetThread), sizeof(void*));
+
+    // mov dstreg, eax
+    X86EmitMovRegReg(dstreg, kEAX);
+
+    X86EmitPopRegs(preservedRegSet & ((1 << kEAX) | (1 << kEDX) | (1 << kECX)));
+
+#ifdef _DEBUG
+    // Trash caller saved regs that we were not told to preserve, and that aren't the dstreg.
+    preservedRegSet |= 1 << dstreg;
+    if (!(preservedRegSet & (1 << kEAX)))
+        X86EmitDebugTrashReg(kEAX);
+    if (!(preservedRegSet & (1 << kEDX)))
+        X86EmitDebugTrashReg(kEDX);
+    if (!(preservedRegSet & (1 << kECX)))
+        X86EmitDebugTrashReg(kECX);
+#endif // _DEBUG
+
+#else // FEATURE_PAL
+
 #ifdef _TARGET_AMD64_
     BYTE code[] = { 0x65,0x48,0x8b,0x04,0x25 };    // mov dstreg, qword ptr gs:[IMM32]
     static const int regByteIndex = 3;
@@ -2386,8 +2412,9 @@ VOID StubLinkerCPU::X86EmitCurrentThreadFetch(X86Reg dstreg)
     X86EmitIndexRegLoad(dstreg, dstreg, sizeof(void *) * (g_TlsIndex & 0xFFFF));
 
     X86EmitIndexRegLoad(dstreg, dstreg, (g_TlsIndex & 0x7FFF0000) >> 16);
+
+#endif // FEATURE_PAL
 }
-#endif // !FEATURE_STUBS_AS_IL
 
 #if defined(_TARGET_X86_)
 
@@ -2716,7 +2743,7 @@ VOID StubLinkerCPU::EmitSetup(CodeLabel *pForwardRef)
 {
     STANDARD_VM_CONTRACT;
 
-    X86EmitCurrentThreadFetch(kEBX);
+    X86EmitCurrentThreadFetch(kEBX, 0);
 
     // cmp ebx, 0
     static const BYTE b[] = { 0x83, 0xFB, 0x0};
@@ -2956,7 +2983,7 @@ VOID StubLinkerCPU::EmitMethodStubProlog(TADDR pFrameVptr, int transitionBlockOf
 #endif // _TARGET_X86_
 
     // ebx <-- GetThread()
-    X86EmitCurrentThreadFetch(kEBX);
+    X86EmitCurrentThreadFetch(kEBX, 0);
 
 #if _DEBUG
 
diff --git a/src/vm/i386/stublinkerx86.h b/src/vm/i386/stublinkerx86.h
index d523bb0461..50dc3b35a5 100644
--- a/src/vm/i386/stublinkerx86.h
+++ b/src/vm/i386/stublinkerx86.h
@@ -219,7 +219,7 @@ class StubLinkerCPU : public StubLinker
         VOID X86EmitLeaRIP(CodeLabel *target, X86Reg reg);
 #endif
 
-        VOID X86EmitCurrentThreadFetch(X86Reg dstreg);
+        VOID X86EmitCurrentThreadFetch(X86Reg dstreg, unsigned preservedRegSet);
         
         VOID X86EmitIndexRegLoad(X86Reg dstreg, X86Reg srcreg, __int32 ofs = 0);
         VOID X86EmitIndexRegStore(X86Reg dstreg, __int32 ofs, X86Reg srcreg);