compile-time fmod was done incorrectly. PR 3316.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@62528 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 81 insertions, 2 deletions

diff --git a/lib/Support/APFloat.cpp b/lib/Support/APFloat.cpp
index 4da7144..fde157d 100644
--- a/lib/Support/APFloat.cpp
+++ b/lib/Support/APFloat.cpp
@@ -1531,7 +1531,7 @@ APFloat::mod(const APFloat &rhs, roundingMode rounding_mode)
   integerPart *x = new integerPart[parts];
   bool ignored;
   fs = V.convertToInteger(x, parts * integerPartWidth, true,
-                          rmNearestTiesToEven, &ignored);
+                          rmTowardZero, &ignored);
   if (fs==opInvalidOp)
     return fs;
 
@@ -1811,7 +1811,9 @@ APFloat::convertToSignExtendedInteger(integerPart *parts, unsigned int width,
   if (exponent < 0) {
     /* Our absolute value is less than one; truncate everything.  */
     APInt::tcSet(parts, 0, dstPartsCount);
-    truncatedBits = semantics->precision;
+    /* For exponent -1 the integer bit represents .5, look at that.
+       For smaller exponents leftmost truncated bit is 0. */
+    truncatedBits = semantics->precision -1U - exponent;
   } else {
     /* We want the most significant (exponent + 1) bits; the rest are
        truncated.  */
diff --git a/test/CodeGen/X86/2009-01-19-fmod-constant-float.ll b/test/CodeGen/X86/2009-01-19-fmod-constant-float.ll
new file mode 100644
index 0000000..0ff2dd4
--- /dev/null
+++ b/test/CodeGen/X86/2009-01-19-fmod-constant-float.ll
@@ -0,0 +1,77 @@
+; RUN: llvm-as < %s | opt -std-compile-opts | llc | grep 1036831949 | count 2
+; RUN: llvm-as < %s | opt -std-compile-opts | llc | grep 3184315597 | count 2
+; check constant folding for 'frem'.  PR 3316.
+
+; ModuleID = 'tt.c'
+target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
+target triple = "i386-apple-darwin9.6"
+
+define float @test1() nounwind {
+entry:
+	%retval = alloca float		; <float*> [#uses=2]
+	%0 = alloca float		; <float*> [#uses=2]
+	%"alloca point" = bitcast i32 0 to i32		; <i32> [#uses=0]
+	%1 = call double @fmod(double 1.000000e-01, double 1.000000e+00) nounwind readonly		; <double> [#uses=1]
+	%2 = fptrunc double %1 to float		; <float> [#uses=1]
+	store float %2, float* %0, align 4
+	%3 = load float* %0, align 4		; <float> [#uses=1]
+	store float %3, float* %retval, align 4
+	br label %return
+
+return:		; preds = %entry
+	%retval1 = load float* %retval		; <float> [#uses=1]
+	ret float %retval1
+}
+
+declare double @fmod(double, double) nounwind readonly
+
+define float @test2() nounwind {
+entry:
+	%retval = alloca float		; <float*> [#uses=2]
+	%0 = alloca float		; <float*> [#uses=2]
+	%"alloca point" = bitcast i32 0 to i32		; <i32> [#uses=0]
+	%1 = call double @fmod(double -1.000000e-01, double 1.000000e+00) nounwind readonly		; <double> [#uses=1]
+	%2 = fptrunc double %1 to float		; <float> [#uses=1]
+	store float %2, float* %0, align 4
+	%3 = load float* %0, align 4		; <float> [#uses=1]
+	store float %3, float* %retval, align 4
+	br label %return
+
+return:		; preds = %entry
+	%retval1 = load float* %retval		; <float> [#uses=1]
+	ret float %retval1
+}
+
+define float @test3() nounwind {
+entry:
+	%retval = alloca float		; <float*> [#uses=2]
+	%0 = alloca float		; <float*> [#uses=2]
+	%"alloca point" = bitcast i32 0 to i32		; <i32> [#uses=0]
+	%1 = call double @fmod(double 1.000000e-01, double -1.000000e+00) nounwind readonly		; <double> [#uses=1]
+	%2 = fptrunc double %1 to float		; <float> [#uses=1]
+	store float %2, float* %0, align 4
+	%3 = load float* %0, align 4		; <float> [#uses=1]
+	store float %3, float* %retval, align 4
+	br label %return
+
+return:		; preds = %entry
+	%retval1 = load float* %retval		; <float> [#uses=1]
+	ret float %retval1
+}
+
+define float @test4() nounwind {
+entry:
+	%retval = alloca float		; <float*> [#uses=2]
+	%0 = alloca float		; <float*> [#uses=2]
+	%"alloca point" = bitcast i32 0 to i32		; <i32> [#uses=0]
+	%1 = call double @fmod(double -1.000000e-01, double -1.000000e+00) nounwind readonly		; <double> [#uses=1]
+	%2 = fptrunc double %1 to float		; <float> [#uses=1]
+	store float %2, float* %0, align 4
+	%3 = load float* %0, align 4		; <float> [#uses=1]
+	store float %3, float* %retval, align 4
+	br label %return
+
+return:		; preds = %entry
+	%retval1 = load float* %retval		; <float> [#uses=1]
+	ret float %retval1
+}