[llvm] r370405 - Fix the build for MSVC builds using M_PI

[Reid Kleckner via llvm-commits]

Author: rnk
Date: Thu Aug 29 13:32:53 2019
New Revision: 370405

URL: http://llvm.org/viewvc/llvm-project?rev=370405&view=rev
Log:
Fix the build for MSVC builds using M_PI

Modified:
    llvm/trunk/lib/Target/AMDGPU/AMDGPULegalizerInfo.cpp

Modified: llvm/trunk/lib/Target/AMDGPU/AMDGPULegalizerInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/AMDGPU/AMDGPULegalizerInfo.cpp?rev=370405&r1=370404&r2=370405&view=diff
==============================================================================
--- llvm/trunk/lib/Target/AMDGPU/AMDGPULegalizerInfo.cpp (original)
+++ llvm/trunk/lib/Target/AMDGPU/AMDGPULegalizerInfo.cpp Thu Aug 29 13:32:53 2019
@@ -11,6 +11,13 @@
 /// \todo This should be generated by TableGen.
 //===----------------------------------------------------------------------===//
 
+#if defined(_MSC_VER) || defined(__MINGW32__)
+// According to Microsoft, one must set _USE_MATH_DEFINES in order to get M_PI
+// from the Visual C++ cmath / math.h headers:
+// https://docs.microsoft.com/en-us/cpp/c-runtime-library/math-constants?view=vs-2019
+#define _USE_MATH_DEFINES
+#endif
+
 #include "AMDGPU.h"
 #include "AMDGPULegalizerInfo.h"
 #include "AMDGPUTargetMachine.h"